Membrane that separates the heart from other mediastinal structures; consists of two distinct, fused sublayers: the fibrous pericardium and the parietal pericardium.


Serous membrane that lines the abdominopelvic cavity and covers the organs found there.


The membrane that wraps around the outside of your lungs and lines the inside of your chest cavity.


Two-dimensional, vertical plane that divides the body or organ into right and left sides.


The very thin, fluid-filled space between the parietal and visceral layers.


Thin layer that lines the inner surface of the joint cavity at a synovial joint; produces the synovial fluid.


Thin layer or sheet of cells that covers the outside of the body, organs, and internal cavities.


Innermost layer of the pleura that is superficial to the lungs and extends into the lung fissures.


CrashCourse. (2015, January 6). Introduction to anatomy & physiology: Crash Course A&P #1 [Video]. YouTube. https://youtu.be/uBGl2BujkPQ


Many prefixes that you find in medical terms are common to English language prefixes. A good technique to help with memorization is the following:


Suffixes  are word parts that are located at the end of words. Suffixes can alter the meaning of medical terms. It is important to spell and pronounce suffixes correctly.


Suffixes in medical terms are common to English language suffixes. Suffixes are not always explicitly stated in the definition of a word. It is common that suffixes will not be explicitly stated when defining a medical term in the workplace. However, when transcribing or reading medical reports the suffix is always clearly written. In order to properly spell and pronounce medical terms, it is helpful to learn the suffixes.


Word parts and definitions from “Appendix A: Word Parts and What They Mean” by MedlinePlus and is under public domain.


By the end of this book, you will have identified hundreds of word parts within medical terms. Let’s start with some common medical terms that many non-medically trained people may be familiar with.


Intravenous

Intra/ven/ous – Pertaining to within a vein.

Intra- is a prefix  that means within

ven/o – is a combining form that means vein

-ous is a suffix  that means pertaining to


Notice, when breaking down words that you place slashes between word parts and a slash on each side of a combining form vowel.


Before we begin analyzing the rules let’s complete a short language review that will assist with pronunciation and spelling.


Short Vowels

a, e, i, o, u, and sometimes y are indicated by lower case.


Long Vowels

A, E, I, O, U are indicated by upper case.


Consonants

Consonants are all of the other letters in the alphabet. b, c, d, f, g, h, j, k, l, m, n, p, q, r, s, t, v, w, x, and z.


Language rules are a good place to start when building a medical terminology foundation. Many medical terms are built from word parts and can be translated literally. At first, literal translations sound awkward. Once you build a medical vocabulary and become proficient at using it, the awkwardness will slip away. For example, suffixes will no longer be stated and will be assumed. The definition of intravenous then becomes within the vein.


Since you are at the beginning of building your medical terminology foundation, stay literal when applicable. It should be noted that as with all language rules there are always exceptions and we refer to those as rebels.


Here is a slit-like exit wound. Note that there is no powder or soot
visible.


Displayed here is an entrance at the left and an exit at the right. This
particular bullet struck at an angle to produce the ovoid entrance. Exit
wounds vary considerably in size and shape because the bullet can be
deformed in its transit through the body. There may be no exit wound at
all if the bullet's energy is absorbed by the tissues. Some bullets (such a
a "hollowpoint") are designed to deform so that all their energy will be
converted to tissue damage and not exit.


This is an intermediate range gunshot entrance wound in which there is
powder "tattooing" around the entrance site.


Powder tattooing is seen in this intermediate range gunshot wound.
The actual entrance site is somewhat irregular, because the bullet can
tumble in flight.


Histologic examination of the entrance wound site on the skin
demonstrates black gunshot residue and coagulative necrosis.


With a contact or very close range gunshot wound, it is possible to have blood spatter as well as sooting on the hand of the person firing the weapon.


This is a contact range gunshot entrance wound with grey-black
discoloration from the burned powder.


The abrasion ring, and a very clear muzzle imprint, are seen in this
contact range gunshot wound.


An abrasion ring, formed when the force of the gases entering below the skin blow the skin surface back against the muzzle of the gun, is seen here in this contact range gunshot wound to the right temple.


This is an contact  gunshot entrance wound. Since the barrel contacts
the skin, the gases released by the fired round go into the subcutaneous
tissue and cause the star-shaped laceration. Note also the grey-black
discoloration from the soot, as well as the faint abrasion ring.


Soot is seen on the hand of a suicide victim, giving an indication that he was holding the weapon when it was fired.


The radiograph of the pelvic region shown above reveals a prosthesis for the hip joint necessitated by a femoral fracture in an older person with osteoporosis.Osteoporotic bone is normal in its composition of hydroxyapatite crystal on an osteoid matrix--there is just less bone. Less bone results in weakened bones that are more prone to fractures with trauma, even minor trauma. The areas most affected are: Hip (femoral head and neck), Wrist, Vertebrae. Hip fractures that occur, even with minor falls, can be disabling and confine an elderly person to a wheelchair. It is also possible to surgically put in a prosthetic hip joint. Wrist fractures are common with falls forward with arms extended to break the fall, but the wrist bones break too. Vertebral fractures are of the compressed variety and may be more subtle. Vertebral fractures may result in back pain. Another consequence is shortening or kyphosis (bending over) of the spine. This can lead to the appearance of a "hunched over" appearance that, if severe enough, can even compromise respiratory function because the thorax is reduced in size. Persons suffering fractures are at greater risk for death, not directly from the fracture, but from the complications that come from hospitalization with immobilization, such as pulmonary thromboembolism and pneumonia. Osteoporosis is so common that, on average, about 1 in 2 elderly Caucasian women will have had a fracture. In contrast, only about 1 in 40 men of similar age will have had a fracture. Men start out with a greater bone mass to begin with, so they have a greater reserve against loss. However, that is still a large number of men with osteoporosis. (Binkley, 2009)


The radiograph of the pelvic region is shown above, with an intertrochanteric fracture located in the right femur of an elderly woman with osteoporosis. Below is the postoperative radiograph following surgical repair.Osteoporotic bone is normal in its composition of hydroxyapatite crystal on an osteoid matrix--there is just less bone. Less bone results in weakened bones that are more prone to fractures with trauma, even minor trauma. The areas most affected are: Hip (femoral head and neck), Wrist, Vertebrae. Hip fractures that occur, even with minor falls, can be disabling and confine an elderly person to a wheelchair. It is also possible to surgically put in a prosthetic hip joint. Wrist fractures are common with falls forward with arms extended to break the fall, but the wrist bones break too. Vertebral fractures are of the compressed variety and may be more subtle. Vertebral fractures may result in back pain. Another consequence is shortening or kyphosis (bending over) of the spine. This can lead to the appearance of a "hunched over" appearance that, if severe enough, can even compromise respiratory function because the thorax is reduced in size. Persons suffering fractures are at greater risk for death, not directly from the fracture, but from the complications that come from hospitalization with immobilization, such as pulmonary thromboembolism and pneumonia. Osteoporosis is so common that, on average, about 1 in 2 elderly Caucasian women will have had a fracture. In contrast, only about 1 in 40 men of similar age will have had a fracture. Men start out with a greater bone mass to begin with, so they have a greater reserve against loss. However, that is still a large number of men with osteoporosis. (Binkley, 2009)


Seen here is the upper femur at the hip. There is severe osteoporosis with marked loss of bone density.Osteoporotic bone is normal in its composition of hydroxyapatite crystal on an osteoid matrix--there is just less bone. Less bone results in weakened bones that are more prone to fractures with trauma, even minor trauma. The areas most affected are: Hip (femoral head and neck), Wrist, Vertebrae. Hip fractures that occur, even with minor falls, can be disabling and confine an elderly person to a wheelchair. It is also possible to surgically put in a prosthetic hip joint. Wrist fractures are common with falls forward with arms extended to break the fall, but the wrist bones break too. Vertebral fractures are of the compressed variety and may be more subtle. Vertebral fractures may result in back pain. Another consequence is shortening or kyphosis (bending over) of the spine. This can lead to the appearance of a "hunched over" appearance that, if severe enough, can even compromise respiratory function because the thorax is reduced in size. Persons suffering fractures are at greater risk for death, not directly from the fracture, but from the complications that come from hospitalization with immobilization, such as pulmonary thromboembolism and pneumonia. Osteoporosis is so common that, on average, about 1 in 2 elderly Caucasian women will have had a fracture. In contrast, only about 1 in 40 men of similar age will have had a fracture. Men start out with a greater bone mass to begin with, so they have a greater reserve against loss. However, that is still a large number of men with osteoporosis. (Binkley, 2009)


Vertebral bone with decreased bony spicules of decreased size from osteoporosis is shown  here at  low power microscopically.Osteoporotic bone is normal in its composition of hydroxyapatite crystal on an osteoid matrix--there is just less bone. Less bone results in weakened bones that are more prone to fractures with trauma, even minor trauma. The areas most affected are: Hip (femoral head and neck), Wrist, Vertebrae. Hip fractures that occur, even with minor falls, can be disabling and confine an elderly person to a wheelchair. It is also possible to surgically put in a prosthetic hip joint. Wrist fractures are common with falls forward with arms extended to break the fall, but the wrist bones break too. Vertebral fractures are of the compressed variety and may be more subtle. Vertebral fractures may result in back pain. Another consequence is shortening or kyphosis (bending over) of the spine. This can lead to the appearance of a "hunched over" appearance that, if severe enough, can even compromise respiratory function because the thorax is reduced in size. Persons suffering fractures are at greater risk for death, not directly from the fracture, but from the complications that come from hospitalization with immobilization, such as pulmonary thromboembolism and pneumonia. Osteoporosis is so common that, on average, about 1 in 2 elderly Caucasian women will have had a fracture. In contrast, only about 1 in 40 men of similar age will have had a fracture. Men start out with a greater bone mass to begin with, so they have a greater reserve against loss. However, that is still a large number of men with osteoporosis. (Binkley, 2009)


Vertebral bone with osteoporosis demonstrates a compressed fracture grossly. Note the narrowing of the compressed vertebral body compared to the other vertebral bodies.Osteoporotic bone is normal in its composition of hydroxyapatite crystal on an osteoid matrix--there is just less bone. Less bone results in weakened bones that are more prone to fractures with trauma, even minor trauma. The areas most affected are: Hip (femoral head and neck), Wrist, Vertebrae. Hip fractures that occur, even with minor falls, can be disabling and confine an elderly person to a wheelchair. It is also possible to surgically put in a prosthetic hip joint. Wrist fractures are common with falls forward with arms extended to break the fall, but the wrist bones break too. Vertebral fractures are of the compressed variety and may be more subtle. Vertebral fractures may result in back pain. Another consequence is shortening or kyphosis (bending over) of the spine. This can lead to the appearance of a "hunched over" appearance that, if severe enough, can even compromise respiratory function because the thorax is reduced in size. Persons suffering fractures are at greater risk for death, not directly from the fracture, but from the complications that come from hospitalization with immobilization, such as pulmonary thromboembolism and pneumonia. Osteoporosis is so common that, on average, about 1 in 2 elderly Caucasian women will have had a fracture. In contrast, only about 1 in 40 men of similar age will have had a fracture. Men start out with a greater bone mass to begin with, so they have a greater reserve against loss. However, that is still a large number of men with osteoporosis. (Binkley, 2009)


Vertebral bone with osteoporosis demonstrates decreased bone mass with fewer and narrower bony spicules.Osteoporotic bone is normal in its composition of hydroxyapatite crystal on an osteoid matrix--there is just less bone. Less bone results in weakened bones that are more prone to fractures with trauma, even minor trauma. The areas most affected are: Hip (femoral head and neck), Wrist, Vertebrae. Hip fractures that occur, even with minor falls, can be disabling and confine an elderly person to a wheelchair. It is also possible to surgically put in a prosthetic hip joint. Wrist fractures are common with falls forward with arms extended to break the fall, but the wrist bones break too. Vertebral fractures are of the compressed variety and may be more subtle. Vertebral fractures may result in back pain. Another consequence is shortening or kyphosis (bending over) of the spine. This can lead to the appearance of a "hunched over" appearance that, if severe enough, can even compromise respiratory function because the thorax is reduced in size. Persons suffering fractures are at greater risk for death, not directly from the fracture, but from the complications that come from hospitalization with immobilization, such as pulmonary thromboembolism and pneumonia. Osteoporosis is so common that, on average, about 1 in 2 elderly Caucasian women will have had a fracture. In contrast, only about 1 in 40 men of similar age will have had a fracture. Men start out with a greater bone mass to begin with, so they have a greater reserve against loss. However, that is still a large number of men with osteoporosis. (Binkley, 2009)


Normal vertebral bone is shown under polarized light microscopy. Note the normal lamellar sturcutre of the bone spicules.Osteoporotic bone is normal in its composition of hydroxyapatite crystal on an osteoid matrix--there is just less bone. Less bone results in weakened bones that are more prone to fractures with trauma, even minor trauma. The areas most affected are: Hip (femoral head and neck), Wrist, Vertebrae. Hip fractures that occur, even with minor falls, can be disabling and confine an elderly person to a wheelchair. It is also possible to surgically put in a prosthetic hip joint. Wrist fractures are common with falls forward with arms extended to break the fall, but the wrist bones break too. Vertebral fractures are of the compressed variety and may be more subtle. Vertebral fractures may result in back pain. Another consequence is shortening or kyphosis (bending over) of the spine. This can lead to the appearance of a "hunched over" appearance that, if severe enough, can even compromise respiratory function because the thorax is reduced in size. Persons suffering fractures are at greater risk for death, not directly from the fracture, but from the complications that come from hospitalization with immobilization, such as pulmonary thromboembolism and pneumonia. Osteoporosis is so common that, on average, about 1 in 2 elderly Caucasian women will have had a fracture. In contrast, only about 1 in 40 men of similar age will have had a fracture. Men start out with a greater bone mass to begin with, so they have a greater reserve against loss. However, that is still a large number of men with osteoporosis. (Binkley, 2009)


Normal vertebral bone and marrow is demonstrated at low power microscopically. Note the size and number of bone spicules.Osteoporotic bone is normal in its composition of hydroxyapatite crystal on an osteoid matrix--there is just less bone. Less bone results in weakened bones that are more prone to fractures with trauma, even minor trauma. The areas most affected are: Hip (femoral head and neck), Wrist, Vertebrae. Hip fractures that occur, even with minor falls, can be disabling and confine an elderly person to a wheelchair. It is also possible to surgically put in a prosthetic hip joint. Wrist fractures are common with falls forward with arms extended to break the fall, but the wrist bones break too. Vertebral fractures are of the compressed variety and may be more subtle. Vertebral fractures may result in back pain. Another consequence is shortening or kyphosis (bending over) of the spine. This can lead to the appearance of a "hunched over" appearance that, if severe enough, can even compromise respiratory function because the thorax is reduced in size. Persons suffering fractures are at greater risk for death, not directly from the fracture, but from the complications that come from hospitalization with immobilization, such as pulmonary thromboembolism and pneumonia. Osteoporosis is so common that, on average, about 1 in 2 elderly Caucasian women will have had a fracture. In contrast, only about 1 in 40 men of similar age will have had a fracture. Men start out with a greater bone mass to begin with, so they have a greater reserve against loss. However, that is still a large number of men with osteoporosis. (Binkley, 2009)


Normal vertebral bone is shown here.Osteoporotic bone is normal in its composition of hydroxyapatite crystal on an osteoid matrix--there is just less bone. Less bone results in weakened bones that are more prone to fractures with trauma, even minor trauma. The areas most affected are: Hip (femoral head and neck), Wrist, Vertebrae. Hip fractures that occur, even with minor falls, can be disabling and confine an elderly person to a wheelchair. It is also possible to surgically put in a prosthetic hip joint. Wrist fractures are common with falls forward with arms extended to break the fall, but the wrist bones break too. Vertebral fractures are of the compressed variety and may be more subtle. Vertebral fractures may result in back pain. Another consequence is shortening or kyphosis (bending over) of the spine. This can lead to the appearance of a "hunched over" appearance that, if severe enough, can even compromise respiratory function because the thorax is reduced in size. Persons suffering fractures are at greater risk for death, not directly from the fracture, but from the complications that come from hospitalization with immobilization, such as pulmonary thromboembolism and pneumonia. Osteoporosis is so common that, on average, about 1 in 2 elderly Caucasian women will have had a fracture. In contrast, only about 1 in 40 men of similar age will have had a fracture. Men start out with a greater bone mass to begin with, so they have a greater reserve against loss. However, that is still a large number of men with osteoporosis. (Binkley, 2009)


An  expression quantitative trait locus  ( eQTL ) is a type of  quantitative trait locus  (QTL), a genomic  locus  (region of DNA) that is associated with  phenotypic  variation for a specific, quantifiable  trait . While the term QTL can refer to a wide range of phenotypic traits, the more specific eQTL refers to traits measured by  gene expression , such as  mRNA levels . [ 1 ] [ 2 ]  Although named "expression QTLs", not all measures of gene expression can be used for eQTLs. For example, traits quantified by protein levels are instead referred to as protein QTLs (pQTLs).


An expression quantitative trait is an amount of an  mRNA  transcript or a  protein . These are usually the product of a single  gene  with a specific chromosomal location. This distinguishes expression quantitative traits from most  complex traits , which are not the product of the expression of a single gene. Chromosomal loci that explain variance in expression traits are called eQTLs. eQTLs located near the gene-of-origin (gene which produces the transcript or protein) are referred to as  local eQTLs  or  cis-eQTLs.  By contrast, those located distant from their gene of origin, often on different chromosomes, are referred to as  distant eQTLs  or  trans-eQTLs . [ 3 ]   [ 4 ]  The first genome-wide study of gene expression was carried out in yeast and published in 2002. [ 5 ]   The initial wave of eQTL studies employed microarrays to measure genome-wide gene expression; more recent studies have employed massively parallel  RNA sequencing . Many  expression  QTL studies were performed in plants and animals, including humans, [ 6 ]  non-human primates [ 7 ] [ 8 ]  and mice. [ 9 ]


Some cis eQTLs are detected in many  tissue  types but the majority of trans eQTLs are tissue-dependent (dynamic). [ 10 ]  eQTLs may act in  cis  (locally) or  trans  (at a distance) to a  gene . [ 11 ]  The abundance of a gene  transcript  is directly modified by  polymorphism  in  regulatory elements . Consequently, transcript abundance might be considered as a quantitative trait that can be mapped with considerable power. These have been named expression  QTLs  (eQTLs). [ 12 ]  The combination of  whole-genome genetic association studies   and the measurement of global  gene expression  allows the systematic identification of eQTLs. By assaying gene
expression and  genetic variation  simultaneously on a genome-wide basis in a large number of individuals, statistical genetic methods can be used to map the genetic factors that underpin individual differences in quantitative levels of expression of many thousands of
transcripts. [ 13 ]  Studies have shown that  single nucleotide polymorphisms  (SNPs) reproducibly associated with complex disorders  [ 14 ]  as well as certain pharmacologic phenotypes  [ 15 ]  are found to be significantly enriched for eQTLs, relative to frequency-matched control SNPs. The integration of eQTLs with  GWAS  has led to development of the  transcriptome-wide association study  (TWAS) methodology. [ 16 ] [ 17 ]


Mapping eQTLs is done using standard  QTL  mapping methods that test the linkage between variation in expression and genetic polymorphisms. The only considerable difference is that eQTL studies can involve a million or more expression microtraits. Standard gene mapping software packages can be used, although it is often faster to use custom code such as QTL Reaper or the web-based eQTL mapping system  GeneNetwork . GeneNetwork hosts many large eQTL mapping data sets and provide access to fast algorithms to map single loci and  epistatic  interactions. As is true in all QTL mapping studies, the final steps in  defining DNA variants that cause variation in traits are usually difficult and require a second round of experimentation.  This is especially the case for trans eQTLs that do not benefit from the strong prior probability that relevant variants are in the immediate vicinity of the parent gene. Statistical, graphical, and bioinformatic methods are used to evaluate positional candidate genes and entire systems of interactions. [ 18 ] [ 19 ]  The development of single cell technologies, and parallel advances in statistical methods has made it possible to define even subtle changes in eQTLs as cell-states change. [ 20 ] [ 21 ]


A  quantitative trait locus  ( QTL ) is a  locus  (section of  DNA ) that correlates with variation of a  quantitative trait  in the  phenotype  of a  population  of  organisms . [ 1 ]  QTLs are mapped by identifying which molecular markers (such as  SNPs  or  AFLPs ) correlate with an observed trait. This is often an early step in identifying the actual  genes  that cause the trait variation.


A  quantitative trait locus  ( QTL ) is a region of  DNA  which is associated with a particular  phenotypic   trait , which varies in degree and which can be attributed to  polygenic  effects, i.e., the product of two or more  genes , and their environment. [ 2 ]  These QTLs are often found on different  chromosomes . The number of QTLs which explain variation in the phenotypic trait indicates the  genetic architecture  of a trait. It may indicate that plant height is controlled by many genes of small effect, or by a few genes of large effect. [ citation needed ]


Typically, QTLs underlie continuous  traits  (those traits which vary continuously, e.g. height) as opposed to discrete traits (traits that have two or several character values, e.g. red hair in humans, a recessive trait, or smooth vs. wrinkled peas used by  Mendel  in his experiments).


Moreover, a single  phenotypic  trait is usually determined by many genes. Consequently, many QTLs are associated with a single trait.
Another use of QTLs is to identify  candidate genes  underlying a trait. The DNA sequence of any genes in this region can then be compared to a database of DNA for genes whose function is already known, this task being fundamental for marker-assisted crop improvement. [ 3 ]


Mendelian inheritance  was rediscovered at the beginning of the 20th century. As  Mendel 's ideas spread, geneticists began to connect Mendel's rules of inheritance of single factors to  Darwinian evolution . For early geneticists, it was not immediately clear that the smooth variation in traits like body size (i.e.,  incomplete dominance ) was caused by the inheritance of single genetic factors. Although  Darwin  himself observed that inbred features of fancy pigeons were inherited in accordance with Mendel's laws (although Darwin did not actually know about Mendel's ideas when he made the observation), it was not obvious that these features selected by fancy pigeon breeders can similarly explain quantitative variation in nature. [ 4 ]


An early attempt by  William Ernest Castle  to unify the laws of Mendelian inheritance with Darwin's theory of speciation invoked the idea that species become distinct from one another as one species or the other acquires a novel Mendelian factor. [ 5 ]  Castle's conclusion was based on the observation that novel traits that could be studied in the lab and that show Mendelian inheritance patterns reflect a large deviation from the wild type, and Castle believed that acquisition of such features is the basis of "discontinuous variation" that characterizes speciation. [ 5 ]  Darwin discussed the inheritance of similar mutant features but did not invoke them as a requirement of speciation. [ 4 ]  Instead Darwin used the emergence of such features in breeding populations as evidence that mutation can occur at random within breeding populations, which is a central premise of his model of selection in nature. [ 4 ]  Later in his career, Castle would refine his model for speciation to allow for small variation to contribute to speciation over time. He also was able to demonstrate this point by selectively breeding laboratory populations of rats to obtain a hooded phenotype over several generations. [ 6 ]


Castle's was perhaps the first attempt made in the scientific literature to direct evolution by artificial selection of a trait with continuous underlying variation, however the practice had previously been widely employed in the development of  agriculture  to obtain livestock or plants with favorable features from populations that show quantitative variation in traits like body size or grain yield. [ citation needed ]


Castle's work was among the first to attempt to unify the recently rediscovered laws of Mendelian inheritance with Darwin's theory of evolution. Still, it would be almost thirty years until the theoretical framework for evolution of  complex traits  would be widely formalized. [ 7 ]  In an early summary of the theory of evolution of continuous variation,  Sewall Wright , a graduate student who trained under Castle, summarized contemporary thinking about the genetic basis of quantitative natural variation: "As genetic studies continued, ever smaller differences were found to mendelize, and any character, sufficiently investigated, turned out to be affected by many factors." [ 7 ]  Wright and others formalized population genetics theory that had been worked out over the preceding 30 years explaining how such traits can be inherited and create stably breeding populations with unique characteristics. Quantitative trait genetics today leverages Wright's observations about the statistical relationship between genotype and phenotype in families and populations to understand how certain genetic features can affect variation in natural and derived populations. [ citation needed ]


Polygenic inheritance  refers to inheritance of a  phenotypic  characteristic (trait) that is attributable to two or more  genes  and can be measured quantitatively.  Multifactorial inheritance  refers to polygenic inheritance that also includes interactions with the environment. Unlike  monogenic traits , polygenic traits do not follow patterns of  Mendelian inheritance  (discrete categories). Instead, their phenotypes typically vary along a continuous gradient depicted by a  bell curve . [ 8 ]


An example of a polygenic trait is  human skin color  variation. Several genes factor into determining a person's natural skin color, so modifying only one of those genes can change skin color slightly or in some cases, such as for  SLC24A5 , moderately. Many disorders with  genetic components  are polygenic, including  autism ,  cancer ,  diabetes  and numerous others. Most phenotypic characteristics are the result of the interaction of multiple genes. [ citation needed ]


Multifactorially inherited diseases are said to constitute the majority of genetic disorders affecting humans which will result in hospitalization or special care of some kind. [ 9 ] [ 10 ]


Traits controlled both by the environment and by genetic factors are called multifactorial.
Usually, multifactorial traits outside of illness result in what we see as  continuous characteristics  in organisms, especially human organisms such as: height, [ 9 ]  skin color, and body mass. [ 11 ]  All of these phenotypes are complicated by a great deal of give-and-take between genes and environmental effects. [ 9 ]  The continuous distribution of traits such as height and skin color described above, reflects the action of genes that do not manifest typical patterns of dominance and recessiveness. Instead the contributions of each involved locus are thought to be additive. Writers have distinguished this kind of inheritance as  polygenic , or  quantitative inheritance . [ 12 ]


Thus, due to the nature of polygenic traits, inheritance will not follow the same pattern as a simple  monohybrid  or  dihybrid cross . [ 10 ]  Polygenic inheritance can be explained as Mendelian inheritance at many loci, [ 9 ]  resulting in a trait which is  normally-distributed . If  n  is the number of involved loci, then the coefficients of the  binomial expansion  of ( a  +  b ) 2n  will give the frequency of distribution of all  n  allele  combinations . For sufficiently high values of  n , this binomial distribution will begin to resemble a normal distribution. From this viewpoint, a disease state will become apparent at one of the tails of the distribution, past some threshold value. Disease states of increasing severity will be expected the further one goes past the threshold and away from the  mean . [ 12 ]


A mutation resulting in a disease state is often recessive, so both alleles must be mutant in order for the disease to be expressed phenotypically. A disease or syndrome may also be the result of the expression of mutant alleles at more than one locus. When more than one gene is involved, with or without the presence of environmental triggers, we say that the disease is the result of multifactorial inheritance. [ citation needed ]


The more genes involved in the cross, the more the distribution of the  genotypes  will resemble a  normal, or Gaussian  distribution. [ 9 ]  This shows that multifactorial inheritance is polygenic, and genetic frequencies can be predicted by way of a polyhybrid  Mendelian  cross. Phenotypic frequencies are a different matter, especially if they are complicated by environmental factors. [ citation needed ]


The paradigm of polygenic inheritance as being used to define multifactorial disease has encountered much disagreement. Turnpenny (2004) discusses how simple polygenic inheritance cannot explain some diseases such as the onset of Type I diabetes mellitus, and that in cases such as these, not all genes are thought to make an equal contribution. [ 12 ]


The assumption of polygenic inheritance is that all involved loci make an equal contribution to the symptoms of the disease. This should result in a normal (Gaussian) distribution of genotypes. When it does not, the idea of polygenetic inheritance cannot be supported for that illness. [ citation needed ]


The above are well-known examples of diseases having both genetic and environmental components. Other examples involve atopic diseases such as  eczema  or  dermatitis , [ 9 ]   spina bifida  (open spine), and  anencephaly  (open skull). [ 13 ]


While  schizophrenia  is widely believed to be multifactorially genetic by  biopsychiatrists , no characteristic genetic markers have been determined with any certainty. [ citation needed ]


If it is shown that the brothers and sisters of the patient have the disease, then there is a strong chance that the disease is genetic [ citation needed ]  and that the patient will also be a genetic carrier. This is not quite enough as it also needs to be proven that the pattern of inheritance is non-Mendelian. This would require studying dozens, even hundreds of different family pedigrees before a conclusion of multifactorial inheritance is drawn. This often takes several years. [ citation needed ]


If multifactorial inheritance is indeed the case, then the chance of the patient contracting the disease is reduced only if cousins and more distant relatives have the disease. [ 13 ]  While multifactorially-inherited diseases tend to run in families, inheritance will not follow the same pattern as a simple  monohybrid  or  dihybrid cross . [ 10 ]


If a genetic cause is suspected and little else is known about the illness, then it remains to be seen exactly how many genes are involved in the phenotypic expression of the disease. Once that is determined, the question must be answered: if two people have the required genes, why are there differences in expression between them? Generally, what makes the two individuals different are likely to be environmental factors. Due to the involved nature of genetic investigations needed to determine such inheritance patterns, this is not usually the first avenue of investigation one would choose to determine etiology. [ citation needed ]


For organisms whose genomes are known, one might now try to exclude genes in the identified region whose function is known with some certainty not to be connected with the trait in question. If the genome is not available, it may be an option to sequence the identified region and determine the putative functions of genes by their similarity to genes with known function, usually in other genomes. This can be done using  BLAST , an online tool that allows users to enter a primary sequence and search for similar sequences within the BLAST database of genes from various organisms. It is often not the actual gene underlying the phenotypic trait, but rather a region of DNA that is closely linked with the gene [ 14 ]


Another interest of statistical geneticists using QTL mapping is to determine the complexity of the genetic architecture underlying a phenotypic trait. For example, they may be interested in knowing whether a phenotype is shaped by many independent loci, or by a few loci, and do those loci interact. This can provide information on how the phenotype may be evolving. [ 15 ]


In a recent development, classical QTL analyses were combined with gene expression profiling i.e. by  DNA microarrays . Such  expression QTLs (eQTLs)  describe  cis - and  trans -controlling elements for the expression of often disease-associated genes. [ 16 ]  Observed  epistatic effects  have been found beneficial to identify the gene responsible by a cross-validation of genes within the interacting loci with  metabolic pathway - and  scientific literature  databases. [ citation needed ]


The simplest method for QTL mapping is analysis of variance ( ANOVA , sometimes called "marker regression") at the marker loci. In this method, in a backcross, one may calculate a  t-statistic  to compare the averages of the two marker  genotype  groups. For other types of
crosses (such as the intercross), where there are more than two possible genotypes, one uses a more general form of ANOVA, which provides a so-called  F-statistic . The ANOVA approach for QTL mapping has three important weaknesses. First, we do not receive separate estimates of QTL location and QTL effect. QTL location is indicated only by looking at which markers give the greatest differences between genotype group averages, and the apparent QTL effect at a marker will be smaller than the true QTL effect as a result of  recombination  between the marker and the QTL. Second, we must discard individuals whose genotypes are missing at the marker. Third, when the markers are widely spaced, the QTL may be quite far from all markers, and so the power for QTL detection will decrease. [ citation needed ]


Lander and Botstein developed interval mapping, which overcomes the three disadvantages of analysis of variance at marker loci. [ 17 ]  Interval mapping is currently the most popular approach for QTL mapping in experimental crosses. The method makes use of a  genetic map  of the typed markers, and, like analysis of variance, assumes the presence of a single QTL. In interval mapping, each locus is considered one at a time and the logarithm of the  odds ratio  ( LOD score ) is calculated for the model that the given locus is a true QTL. The odds ratio is related to the  Pearson correlation coefficient  between the phenotype and the marker genotype for each individual in the experimental cross. [ 18 ]


The term 'interval mapping' is used for estimating the position of a QTL within two markers (often indicated as 'marker-bracket'). Interval mapping is originally based on the maximum likelihood but there are also very good approximations possible with simple regression. [ citation needed ]


The principle for QTL mapping is:
1) The likelihood can be calculated for a given set of parameters (particularly QTL effect and QTL position) given the observed data on phenotypes and marker genotypes.
2) The estimates for the parameters are those where the likelihood is highest.
3) A significance threshold can be established by permutation testing. [ 19 ]


Conventional methods for the detection of quantitative trait loci (QTLs) are based on a comparison of single QTL models with a model assuming no QTL. For instance in the "interval mapping" method [ 20 ]  the likelihood for a single putative QTL is assessed at each location on the genome. However, QTLs located elsewhere on the genome can have an interfering effect. As a consequence, the power of detection may be compromised, and the estimates of locations and effects of QTLs may be biased (Lander and Botstein 1989; Knapp 1991). Even nonexisting so-called "ghost" QTLs may appear (Haley and Knott 1992; Martinez and Curnow 1992). Therefore, multiple QTLs could be mapped more efficiently and more accurately by using multiple QTL models. [ 21 ]  One popular approach to handle QTL mapping where multiple QTL contribute to a trait is to iteratively scan the genome and add known QTL to the regression model as QTLs are identified. This method, termed  composite interval mapping  determine both the location and effects size of QTL more accurately than single-QTL approaches, especially in small mapping populations where the effect of correlation between genotypes in the mapping population may be problematic. [ citation needed ]


In this method, one performs interval mapping using a subset of marker loci as covariates. These markers serve as proxies for other QTLs to increase the resolution of interval mapping, by accounting for linked QTLs and reducing the residual variation. The key problem with CIM concerns the choice of suitable marker loci to serve as covariates; once these have been chosen, CIM turns the model selection problem into a single-dimensional scan. The choice of marker covariates has not been solved, however. Not surprisingly, the appropriate markers are those closest to the true QTLs, and so if one could find these, the QTL mapping problem would be complete anyway.


Inclusive composite interval mapping  (ICIM) has also been proposed as a potential method for QTL mapping. [ 22 ]


Family-based QTL mapping , or Family-pedigree based mapping (Linkage and  association mapping ), involves multiple families instead of a single family. Family-based QTL mapping has been the only way for mapping of genes where experimental crosses are difficult to make. However, due to some advantages, now plant geneticists are attempting to incorporate some of the methods pioneered in human genetics. [ 23 ]  Using family-pedigree based approach has been discussed (Bink et al. 2008). Family-based linkage and association has been successfully implemented (Rosyara et al. 2009) [ 24 ]


Euphytica 2008, 161:85–96.


Splicing quantitative trait loci  (abbreviated  sQTLs  or  splicing QTLs ) are  quantitative trait loci  that regulate  alternative splicing  of  pre-mRNA . They can be detected using  RNA-seq  data. [ 1 ] [ 2 ]  Methods that have been developed to discover sQTLs include LeafCutter, [ 3 ]  Altrans, Cufflinks, and MISO. [ 4 ]


This  genetics  article is a  stub . You can help Wikipedia by  expanding it .


DNA Research  is an international,  peer-reviewed  journal of  genomics  and DNA research. The journal was established in 1994, and is published by  Oxford University Press  on behalf of the  Kazusa DNA Research Institute . The journal is edited by  Michio Oishi .


In 2014, the journal's  impact factor  was 5.477, ranking 22nd out of 167 in the category 'Genetics & Heredity'. The journal is indexed and abstracted in the following databases:


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See tips for writing articles about academic journals . Further suggestions might be found on the article's  talk page .


The  Encyclopedia of Genetics  ( ISBN   0-12-227080-0 ) is a print  encyclopedia  of  genetics  edited by Sydney Brenner and Jeffrey H. Miller. It has four volumes and 1,700 entries.


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The  Genome News Network  (abbreviated  GNN ) is an online magazine that publishes news articles and educational resources about  genomics  and  medicine . [ 1 ]  It was founded in 1999, with Barbara Culliton as the founding  editor-in-chief . It was originally published by  Celera Genomics . [ 2 ] [ 3 ]  In 2001, the  Institute for Genomic Research  became the magazine's new publisher. [ 4 ]  An article published in  the Lancet Oncology  that year stated that the magazine "...offers news, original articles, the online reference book,  What’s a genome? , and primers on sequencing and assembling the genome – all well  written and illustrated". [ 5 ]  As of 2010, new issues of the magazine were published biweekly. [ 6 ]


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" Our Fragile Intellect " is a 2012 article by American biochemist  Gerald Crabtree , published in the journal  Trends in Genetics . Crabtree's speculative and controversial thesis argues that  human intelligence  peaked sometime between 2,000 and 6,000 years ago and has been in steady decline since the advent of agriculture and increasing urbanization. Modern humans, according to Crabtree, have been losing their intellectual and emotional abilities due to accumulating  gene mutations  that are not being selected against as they once were in our  hunter-gatherer  past. [ 1 ] [ 2 ]  This theory is sometimes referred to as the " Idiocracy  hypothesis". [ 3 ]


Crabtree argues that advancements in modern science allow new predictions to be made about both the past and the future of humanity and we can predict "that our intellectual and emotional abilities are genetically surprisingly fragile". [ 4 ]  Recent studies of genes correlated with human intelligence on the  X chromosome  indicate typical intellectual and emotional activity depends on 10% of genes. Intelligence-dependent (ID) genes appear to be widely distributed throughout the entire genome, leading to a figure of 2,000 and 5,000 genes responsible for our cognitive abilities. Deleterious mutations in these genes can impact normal intellectual and emotional functioning in humans. It is thought that in just the last 120 generations (3000 years), humans have received two or more harmful mutations to these genes, or one every 20-50 generations. [ 4 ] [ 5 ]  Crabtree points out that he loves our society's supportive institutions and wishes that they could be extended to include more of our population. The data that support the theory that our intellectual abilities are particularly susceptible to the accumulation of mutations begins with determinations of the human intergenerational mutation rate. This rate has been determined in several human populations to be about 1.20 x10-8 per position per haploid genome [ 6 ] [ 7 ] [ 8 ] [ 9 ]  with an average father's age of 29.7 years. This rate doubles every 16.5 years with the father's age and ascribes most of the new mutations to the father during the production of sperm. [ 10 ]  In contrast to popular opinion, this figure indicates that the biological clock (in terms of accumulation of deleterious mutations with time) is ticking faster for men than for women. This figure of 1.20 x10-8 mutations per nucleotide per generation predicts that about 45 to 60 new mutations will appear in each generation. These mutations might accumulate or be removed by natural selection. The speculation that the nervous system and the brain would be more sensitive than other cell types and organs to the accumulation of these new mutations was based on the estimate of the fraction of genes necessary for normal development of the nervous system. The data quantifying the number of genes required for normal intellectual development comes from thousands of published studies (about 23,000 on PubMed from the National Library of Medicine) in which scientists have identified a mutated gene or a region of DNA associated with or causing human intellectual disability. These genes may not even be expressed in the brain. For example, the phenylalanine hydroxylase gene is expressed only in the liver, yet its mutation leads to severe intellectual disability due to the accumulation of metabolites. [ 11 ] [ 12 ]  Many of these genes operate like links on a chain rather than a robust network underlining the fragility of our intellectual abilities. For example, mutations of a single nucleotide out of the 3 billion human nucleotides in our genomes in one copy of the ARID1B gene are a common cause of intellectual disability. [ 13 ]  Estimates of the total number of genes that when mutated give rise to intellectual disability is thought to be several thousand, perhaps 10-20% of all human genes, which produces a very large target for random mutations. In addition, neuronal genes tend to be large  [ 14 ] [ 15 ]  and hence increase the size of the genomic target region for random mutations. The simple combination of the number and size of genes required for normal brain development (>1000) and the fact that each new human generation has 45-60 new mutations per genome led Crabtree to suggest that our intellectual abilities are particularly genetically fragile over many generations. Seemingly the only practical implication of this theory is that perhaps men should have their children when they are young and that women should prefer younger men for mates.


Several counterarguments are presented. The  Flynn effect , for example, shows an apparent increase in IQ around the world since 1930. Crabtree attributes the rise in IQ to advancements in environmental and public health measures as well as improved education and other factors. The Flynn effect also shows, argues Crabtree, not an increase in intelligence, but more intelligent test taking. [ 4 ] [ 16 ]


Kevin Mitchell, associate professor at the Smurfit Institute of Genetics at  Trinity College Dublin  agreed that genetic mutations could harm the development of the brain in humans and diminish intelligence; new mutations would become apparent in new generations. However, Mitchell criticizes Crabtree for failing to acknowledge the role of  natural selection . According to Mitchell, natural selection "definitely has the ability to weed out new mutations that significantly impair intellectual ability". Mitchell describes Crabtree's argument as a conceptual fallacy and says Crabtree is "thinking about things in a wrong way". [ 2 ]


Biologist  Steve Jones , Emeritus Professor of Genetics at  University College London  questioned the journal's decision to publish the paper, calling the study "a classic case of Arts Faculty science. Never mind the hypothesis, give me the data, and there aren't any". [ 17 ]  Crabtree acknowledges that the data isn't there because a slow genetic deterioration in intelligence can't be detected by comparing it to people today. Instead, Crabtree argues that he is synthesizing already existing data and making a purely mathematical argument that estimates the probability of the number of new mutations that could result in cognitive deficits in future generations. [ 18 ]


Anthropologist  Robin Dunbar  at  Oxford University  argues against Crabtree's position that brain size was driven by tool use. Instead, Dunbar argues that the social environment drives intelligence. "In reality what has driven human and primate brain evolution is the complexity of our social world", says Dunbar. "That complex world is not going to go away. Doing things like deciding who to have as a mate or how best to rear your children will be with us forever." [ 19 ]


Writer  Andrew Brown  notes that Crabtree's paper represents a familiar, reoccurring notion in both fiction and evolutionary biology. "The idea that civilized man is a degenerate and self-domesticated variation on the wild type is partly a cultural trope, a result of the anxieties of industrialized life", writes Brown. The idea, Brown observes, was popular in the early 20th century fiction of  E. M. Forster  (" The Machine Stops ") and  Jack London  ( The Scarlet Plague ). It could also be found in the work of biologists such as  Ronald Fisher , who espoused similar concepts in  The Genetical Theory of Natural Selection  (1930). The most important parts of Fisher's book, Brown writes, expounds on the theme that "civilization is dreadfully threatened by the way the lower classes outbreed the aristocracy." Brown finds related sentiments expressed in the work of  W. D. Hamilton , who believed that the "life-saving efforts of modern medicine" threatened the human genome. [ 20 ]


" Sickle Cell Anemia, a Molecular Disease " is a 1949 scientific paper by  Linus Pauling ,  Harvey A. Itano ,  Seymour J. Singer  and  Ibert C. Wells  that established  sickle-cell anemia  as a  genetic disease  in which affected individuals have a different form of the  metalloprotein   hemoglobin  in their blood.  The paper, published in the November 25, 1949 issue of  Science , reports a difference in  electrophoretic mobility  between hemoglobin from healthy individuals and those with sickle-cell anemia, with those with  sickle cell trait  having a mixture of the two types.  The paper suggests that the difference in electrophoretic mobility is probably due to a different number of ionizable  amino acid  residues in the protein portion of hemoglobin (which was confirmed in 1956 by  Vernon Ingram ), and that this change in molecular structure is responsible for the sickling process.  It also reports the genetic basis for the disease, consistent with the simultaneous genealogical study by  James V. Neel : those with sickle-cell anemia are homozygous for the disease gene, while heterozygous individuals exhibit the usually asymptomatic condition of sickle cell trait. [ 1 ]


The paper introduced the concept of a "molecular disease", and is considered a major impetus to the development of  molecular medicine .  The paper helped establish that genes control not just the presence or absence of enzymes (as genetics had shown in the early 1940s) but also the specific structure of protein molecules. [ 2 ]   It was also an important triumph in the efforts of Pauling and others to apply the instruments and methods of the physical sciences to biology, and Pauling used it promote such research and attract funding. [ 3 ]


Linus Pauling was a prominent physical chemist at the  California Institute of Technology  (a main focal point of  Warren Weaver 's efforts to promote what he called "molecular biology" through  Rockefeller Foundation  grants).  In the mid-1930s, Pauling turned his attention to the physical and chemical nature of hemoglobin.  In 1946, he set graduate student  Harvey Itano  (who had been previously trained as a physician) the task of finding differences in hemoglobin that might explain sickle cell disease.  After failing to find any differences in size, weight, or acid-base titration (despite the advanced instruments available at Caltech), Itano found that oxygen could inhibit the sickling process while various  reducing agents  could speed it up; this was the basis of Pauling and Itano's first publication on the disease.  Itano also found that the globin portion of sickle cell hemoglobin had a barely detectable difference in electrical charge. [ 4 ]


To measure this electrical difference precisely, Pauling assigned graduate student John Singer to work with Itano and another medical researcher, Ibert C. Wells, before Pauling left in early 1948 for a guest lectureship in England.  Using a "Tiselius Apparatus" to perform  free-boundary electrophoresis , Pauling's three researchers were able to estimate that molecules of sickle-cell hemoglobin had about three more positive charges than normal hemoglobin. [ 3 ] [ 4 ]   They also estimated that blood from those with sickle cell trait was a mixture of 60 percent normal hemoglobin and 40 percent sickle-cell hemoglobin. [ 1 ]   Near the end of the project, they learned of parallel results by geneticist James V. Neel, who demonstrated the inheritance pattern of the disease by traditional genetic methods; both Neel's work and that of Pauling's group were published in the same issue of  Science . [ 3 ]


Following the 1949 paper, Itano left the Pauling laboratory to work with Neel; in the following years Itano and Neel used electrophoresis to identify a number of other human hemoglobin variants, including some associated with other diseases.  At Caltech, a comparison of the amino acid content of normal and sickle cell hemoglobins showed that there were several differences in chemical makeup, but did not explain the difference in electric charge that made electrophoretic separation possible.  The cause of this difference was pinpointed in 1956 and 1957, when  Vernon Ingram  used protein fingerprinting (a combination of  electrophoresis  and  chromatography ) to show that the key difference between normal hemoglobins and sickle cell hemoglobins was a single difference in one chain of the protein: a  glutamic acid  residue on the normal hemoglobin in place of a  valine  residue on the sickle cell hemoglobin. [ 5 ]


The molecular disease concept put forward in the 1949 paper also became the basis for Linus Pauling's view of evolution.  In the 1960s, by which time it had been shown that sickle cell trait  confers resistance to malaria  and so the gene had both positive and negative effects and demonstrated  heterozygote advantage , Pauling suggested that molecular diseases were actually the basis of evolutionary change. [ 6 ]   He also advocated  eugenic  policies, such as marking all who carry the sickle cell trait and other molecular disease genes, to reduce the number of children born with genetic diseases. [ 7 ]


The  Talking Glossary of Genetic Terms  is an audio/visual glossary of 256 terms prepared and hosted by the  National Human Genome Research Institute  in the  United States . [ 1 ]


The  National Human Genome Research Institute (NHGRI) created the Talking Glossary of Genetic Terms to help people without scientific backgrounds understand the terms and concepts used in genetic  research . Simply click on the term of interest to open a page with a wealth of information, including the term's  pronunciation , audio information, images and additional links to related terms. Students, teachers and parents will find the  glossary  an easy-to-use, always available learning source on genetics.


The first version was published in  English  online in September 1998 by the NHGRI Office of Science Education under the title of " Talking Glossary of Genetics ". [ 2 ]  The Spanish-language version was released 18 months later. [ 2 ]


A new multimedia, and significantly updated, version of the English Talking Glossary of Genetics was released by the National Human Genome Research Institute in October, 2009. An identical update of the Spanish-language version was released in October, 2011. In September, 2011, an iPhone App of the English Talking Glossary was released by NHGRI and made available as a free download in the Apple App store. The App version contains all 3-D animations, high quality illustrations, the "Test Your Gene IQ" quiz, and similar user functions such as "Suggest a Term" and "Mail This Term to a Friend."


The original version had been based on simple HTML entries and was developed in the mid-1990s at a time when dial-up modems were commonly used to access the internet at speeds as low as 14.4 kps. That version of the Talking Glossary contained 178 terms and talking explanations of each term, as well as about 70 black-and-white illustrations.


The new, and current, versions of the Talking Glossary featured a substantial visual, content, and functional upgrade to the popular online tool. The new Glossaries are built on a vibrant FLASH-based web design employing colorful pages, clear digital audio files, color illustrations, 3-D animations, a "Test Your Gene IQ" function, real-time applets to "cite a term in a paper", "suggest a term", and "share a term" via email.


The list of terms was expanded to 256 entries. Terms were chosen using a number of metrics including a review of the online usage of the glossary over the previous decade. Some terms were dropped as a result, and a large number of terms were added. Other metrics used to determine terms included a scan of the most commonly used science books in U.S. K-12 classrooms for terms and concepts, review of all terms suggested by users using the glossary term suggestion function, and a scan of public media and scientific publications for terms.


Developing the Talking Glossary:


The Talking Glossary of Genetics is a science learning tool developed by the National Human Genome Research Institute (NHGRI) at the National Institutes of Health (NIH). NHGRI oversaw the NIH's role in the Human Genome Project, the international research effort aimed at mapping the genes in the human body and developing tools for gene discovery.


Many of the Talking Glossary terms are commonly used today in news reports, by researchers and medical professionals, in classrooms and, increasingly, as part of daily conversation.


In this light, the Glossary was designed to enable people without a formal scientific background to better understand the terms and concepts behind genetic research. Special attention has been paid to users who are learning or teaching genetics in the classroom. However, the Glossary is designed to be valuable for a much wider audience including patients, doctors, nurses, parents, and professionals dealing with genetic concepts and terminology, such as judges, lawyers, law enforcement officials, and others.


The process of developing the Talking Glossary began by examining some of the most popular American middle school and high school science textbooks. Genetics-related terms from these textbooks provided the foundation for the Talking Glossary. These terms are associated with biological concepts addressed by the National Science Education Standards and common in high school and college biology courses. Additional terms not found in textbooks were added to the glossary, reflecting the rapid pace of genetic research and its coverage in the media.


Written Definitions:


Each glossary entry has a written definition that has been reviewed for clarity and accuracy by teams of science educators and genetic researchers. All of the definitions were written by the same Ph.D.-level science writer for consistency and accuracy.


Illustrations:


Most terms have professionally drawn illustrations to further explain a meaning or concept, or place them in context of the cell or a similar biological setting as a means to better explain the term. All illustrations are provided by the medical illustrator/artist at the NHGRI to enable continuity and maximize re-use in learning tools such as slide shows. All illustrations are copyright free.


Each illustration can be viewed as a webpage within the glossary or downloaded as a high-quality PDF file or PowerPoint slide.


3–D Animations:


The Glossary contains many terms that are illustrated with 3-D movie animations. The animations have a non-descript musical background and are purposely not narrated to maximize use. These animations may be played alone or simultaneously with the spoken definition of the term. All cellular organelles have animation sequences, as do many key terms such as gene, cell, ACGT, and chromosome.


Spoken Explanations of Glossary Terms:


Each term features a friendly and informative spoken explanation that can be heard on any computer with sound capabilities by clicking on the "Listen" button on each term page. Spoken explanations can be paused at any point for user convenience.


Each speaker comments on, or defines, terms relevant to their personal field of study. For example, leading cancer researchers comment on cancer, genetic counselors explain  genetic testing  terms, and expert gene hunters tackle the many terms surrounding the search for or mapping of genes. All speakers are actively working in the field, and most work at NHGRI.


The written definition provides a reasonable definition for each term. The spoken definition is not the same as the written definition. Instead, each speaker was asked to provide information different than the written definition that would expand the listener’s understanding of the term. Speakers were also asked to explain the term to the average person, not another scientist. No speaker was allowed to read, all recorded explanations are spontaneous.


How to Pronounce a Term:


Much of the terminology of genetics and biology is unique in its pronunciation. Below each term name is a “Pronunciation” button. Click the button to hear the term spoken. Each term, regardless of its name, is pronounced.


Information On Each Speaker:


A brief biography and photograph of each speaker accompanies terms listed in the glossary. This enables the user to examine the speaker's credentials and learn more about their research interests.


Related Terms:


If either a written or spoken definition uses other Talking Glossary terms in its text or dialogue, these terms appear in the “Related Terms” listing at the bottom of each term page. The related terms list also includes Glossary terms that reviewers of the Glossary felt would be helpful to the user.


“Test Your Gene Knowledge” Quiz:


The Talking Glossary offers a 10-term quiz designed to be both fun and instructional. The quiz can be accessed from every term page in the Glossary. Users can choose to test their knowledge about terms commonly found in K-16 science classrooms or, more generally, in popular news reports or conversation. The quiz randomly chooses terms from the Talking Glossary and asks the user to select a term name to match the definition shown. Hints are available for each question, and at the end of the quiz all users are able to print a "Certificate of Completion" that includes the date the test was taken, number of correct answers, and the user's name.
 About PDF and PPT Files:


PDF (Portable Document Format) files are high-quality image files that appear and print like the original artwork. These finely detailed illustrations will download quickly and include required fonts. PDF files of Glossary illustrations can be downloaded and saved for later uses, such as overhead transparencies, school reports, or for handouts in class or at a talk or other event. Each PDF file is formatted to print on regular printer paper or standard overhead transparency.


Illustrations are also downloadable as PowerPoint slides. These files can be easily copied and pasted into any existing PowerPoint presentation or can serve as a starting point for a new presentation. These slides are designed to provide lecturers with an easy-to-use and convenient source of illustrations for genetic terms and concepts.


Microbial genetics  is a subject area within  microbiology  and  genetic engineering . Microbial genetics studies microorganisms for different purposes. The microorganisms that are observed are bacteria and archaea. Some fungi and protozoa are also subjects used to study in this field. The studies of microorganisms involve studies of genotype and expression system. Genotypes are the inherited compositions of an organism. (Austin, "Genotype," n.d.) Genetic Engineering is a field of work and study within microbial genetics. [ 1 ]  The usage of recombinant DNA technology is a process of this work. [ 1 ]  The process involves creating recombinant DNA molecules through manipulating a DNA sequence. [ 1 ]  That DNA created is then in contact with a host organism. Cloning is also an example of genetic engineering. [ 1 ]


Since the discovery of microorganisms by Robert Hooke and Antoni van Leeuwenhoek during the period 1665-1885 [ 2 ]  they have been used to study many processes and have had applications in various areas of study in genetics.
For example: Microorganisms' rapid growth rates and short generation times are used by scientists to study evolution. Robert Hooke and Antoni van Leeuwenhoek discoveries involved depictions, observations, and descriptions of microorganisms. [ 3 ]  Mucor is the microfungus that Hooke presented and gave a depiction of. [ 4 ]  His contribution being, Mucor as the first microorganism to be illustrated. Antoni van Leeuwenhoek’s contribution to the microscopic protozoa and microscopic bacteria yielded to scientific observations and descriptions. [ 4 ]  These contributions were accomplished by a simple microscope, which led to the understanding of microbes today and continues to progress scientists understanding.   [ 5 ]
Microbial genetics also has applications in being able to study processes and pathways that are similar to those found in humans such as  drug metabolism . [ 6 ]


Microbial genetics can focus on Charles Darwin's work and scientists have continued to study his work and theories by the use of microbes. [ 7 ]  Specifically, Darwin's theory of natural selection is a source used. Studying evolution by using microbial genetics involves scientists looking at evolutionary balance. [ 1 ]  An example of how they may accomplish this is studying natural selection or drift of microbes. [ 7 ]  Application of this knowledge comes from looking for the presence or absence in a variety of different ways. [ 7 ]  The ways include identifying certain pathways, genes, and functions. Once the subject is observed, scientist may compare it to a sequence of a conserved gene. [ 1 ]  The process of studying microbial evolution in this way lacks the ability to give a time scale of when the evolution took place. [ 7 ]  However, by testing evolution in this way, scientist can learn the rates and outcomes of evolution. Studying the relationship between microbes and the environment is a key component to microbial genetics evolution. [ 8 ]


Bacteria  have been on this planet for approximately 3.5 billion years, and are classified by their shape. [ 9 ]   Bacterial genetics  studies the mechanisms of their heritable information, their  chromosomes ,  plasmids ,  transposons , and  phages . [ 10 ]


Gene transfer systems that have been extensively studied in bacteria include  genetic transformation ,  conjugation  and  transduction .   Natural transformation  is a bacterial adaptation for DNA transfer between two cells through the intervening medium. The uptake of donor DNA and its recombinational incorporation into the recipient chromosome depends on the expression of numerous bacterial genes whose products direct this process. [ 11 ] [ 12 ]   In general, transformation is a complex, energy-requiring developmental process that appears to be an adaptation for repairing DNA damage. [ 13 ]


Bacterial conjugation  is the transfer of genetic material between  bacterial cells  by direct cell-to-cell contact or by a bridge-like connection between two cells.  Bacterial conjugation has been extensively studied in  Escherichia coli , but also occurs in other bacteria such as  Mycobacterium smegmatis . Conjugation requires stable and extended contact between a donor and a recipient strain, is  DNase  resistant, and the transferred DNA is incorporated into the recipient chromosome by  homologous recombination .  E. coli  conjugation is mediated by expression of  plasmid  genes, whereas mycobacterial conjugation is mediated by genes on the bacterial chromosome. [ 14 ]


Transduction  is the process by which foreign  DNA  is introduced into a cell by a  virus  or  viral vector .  Transduction is a common tool used by molecular biologists to stably introduce a foreign gene into a host cell's  genome .


Archaea  is a domain of organisms that are  prokaryotic , single-celled, and are thought to have developed 4 billion years ago.  "They have no cell nucleus or any other organelles inside their cells."Archaea replicate asexually in a process known as binary fission. The cell division cycle includes when chromosomes of daughter cells replicate. Because archea have a singular structure chromosome, the two daughter cells separate and cell divides.  Archaea have motility include with  flagella , which is a tail like structure. Archaeal chromosomes replicate from different origins of replication, producing two haploid daughter cells. [ 15 ]  " [ 16 ]  They share a common ancestor with  bacteria , but are more closely related to eukaryotes in comparison to bacteria. [ 17 ]  Some Archaea are able to survive extreme environments, which leads to many applications in the field of genetics. One of such applications is the use of archaeal enzymes, which would be better able to survive harsh conditions  in vitro . [ 18 ]


Gene transfer and genetic exchange have been studied in the  halophilic  archaeon  Halobacterium volcanii  and the  hyperthermophilic  archaeons  Sulfolobus solfataricus  and  Sulfolobus acidocaldarius .   H. volcani  forms cytoplasmic bridges between cells that appear to be used for transfer of DNA from one cell to another in either direction. [ 19 ]   When  S. solfataricus  and  S. acidocaldarius  are exposed to DNA damaging agents, species-specific cellular aggregation is induced. Cellular aggregation mediates chromosomal marker exchange and genetic recombination with high frequency. Cellular aggregation is thought to enhance species specific DNA transfer between  Sulfolobus  cells in order to provide increased repair of damaged DNA by means of  homologous recombination . [ 20 ] [ 21 ] [ 22 ]  Archaea are divided into 3 subgroups which are  halophiles ,  methanogens , and  thermoacidophiles . The first group, methanogens, are archaeabacteria that live in swamps and marshes as well as in the gut of humans. They also play a major role in decay and decomposition with dead organisms. Methanogens are anaerobic organisms, which are killed when they are exposed to oxygen. The second subgroup of archaeabacteria, halophiles are organisms that are present in areas with high salt concentration like the Great Salt Lake and the Dead Sea. The third subgroup thermoacidophiles also called thermophiles, are organisms that live in acidic areas. They are present in area with low pH levels like hot springs and geyers. Most thermophiles are found in the Yellowstone National Park. [ 23 ]


Archaeal Genetics is the study of genes that consist of single nucleus-free cells. [ 24 ]  Archaea have a single, circular chromosomes that contain multiple origins of replication for initiation of DNA synthesis. [ 25 ]  DNA replication of Archaea involves similar processes including initiation, elongation, and termination. The primase used to synthesize a RNA primer varies than in eukaryotes. The primase by archaea is highly derived version of RNA recognition motif(RRM). [ 25 ]  Archaea come from Gram positive bacteria, which both have a single lipid bilayer, which are resistant to antibiotics. Archaea are similar to mitochondria in eukaryotes in that they release energy as adenosine triphosphate (ATP) through the chemical reaction called metabolism. [ 25 ]  Some archaea known as phototrophic archaea use the sun’s energy to produce ATP. ATP synthase is used as photophosphorylation to convert chemicals into ATP. [ 15 ]


Archaea and bacteria are structurally similar even though they are not closely related in the tree of life. The shapes of both bacteria and archaea cells vary from a spherical shape known as coccus or a rod-shape known as bacillus. They are also related with no internal membrane and a cell wall that assists the cell maintaining its shape. Even though archaeal cells have cells walls, they do not contain peptidoglycan, which means archaea do not produce cellulose or chitin.   Archaea are most closely related to eukaryotes due to tRNA present in archaea, but not in bacteria. Archaea have the same ribosomes as eukaryotes that synthesize into proteins. [ 26 ]  Aside from the morphology of archaea and bacteria, there are other differences between these domains. Archaea that live in extreme and harsh environments with low pH levels such as salt lakes, oceans, and in the gut of ruminants and humans are also known as extremophiles. In contrast, bacteria are found in various areas such as plants, animals, soil, and rocks. [ 27 ]


Fungi  can be both multicellular and unicellular organisms, and are distinguished from other  microbes  by the way they obtain nutrients. Fungi secrete  enzymes  into their surroundings, to break down organic matter. [ 9 ]  Fungal genetics uses  yeast , and filamentous fungi as model organisms for eukaryotic genetic research, including  cell cycle  regulation,  chromatin  structure and  gene regulation . [ 28 ]


Studies of the  fungus   Neurospora crassa  have contributed substantially to understanding how  genes  work.   N. crassa  is a type of red bread  mold  of the  phylum   Ascomycota .  It is used as a  model organism  because it is easy to grow and has a  haploid  life cycle that makes  genetic  analysis simple since recessive traits will show up in the offspring. Analysis of genetic recombination is facilitated by the ordered arrangement of the products of  meiosis  in  ascospores .  In its natural environment,  N. crassa  lives mainly in tropical and sub-tropical regions. It often can be found growing on dead plant matter after fires.


Neurospora  was used by  Edward Tatum  and  George Beadle  in their experiments [ 29 ]  for which they won the  Nobel Prize in Physiology or Medicine   in 1958. The results of these experiments led directly to the  one gene-one enzyme hypothesis  that specific  genes  code for specific  proteins . This concept proved to be the opening gun in what became  molecular genetics  and all the developments that have followed from that. [ 30 ]


Saccharomyces cerevisiae  is a  yeast  of the  phylum   Ascomycota .  During vegetative growth that ordinarily occurs when nutrients are abundant,  S. cerevisiae  reproduces by  mitosis  as  diploid  cells. However, when starved, these cells undergo  meiosis  to form  haploid   spores . [ 31 ]    Mating occurs when haploid cells of opposite  mating types  MATa and MATα come into contact.  Ruderfer et al. [ 32 ]  pointed out that, in nature, such contacts are frequent between closely related yeast cells for two reasons. The first is that cells of opposite mating type are present together in the same  acus , the sac that contains the cells directly produced by a single  meiosis , and these cells can mate with each other. The second reason is that  haploid  cells of one mating type, upon cell division, often produce cells of the opposite mating type.  An analysis of the ancestry of natural  S. cerevisiae  strains concluded that outcrossing occurs very infrequently (only about once every 50,000 cell divisions). [ 32 ]   The relative rarity in nature of meiotic events that result from outcrossing suggests that the possible long-term benefits of outcrossing (e.g. generation of diversity) are unlikely to be sufficient for generally maintaining sex from one generation to the next.  Rather, a short-term benefit, such as meiotic recombinational repair of DNA damages caused by stressful conditions (such as starvation) [ 33 ]  may be the key to the maintenance of sex in  S. cerevisiae .


Candida albicans  is a diploid fungus that grows both as a yeast and as a  filament .   C. albicans  is the most common fungal  pathogen  in humans. It causes both debilitating mucosal infections and potentially life-threatening systemic infections.   C. albicans  has maintained an elaborate, but largely hidden, mating apparatus. [ 34 ]   Johnson [ 34 ]  suggested that mating strategies may allow  C. albicans  to survive in the hostile environment of a mammalian host.


Among the 250 known species of  aspergilli , about 33% have an identified sexual state. [ 35 ]   Among those  Aspergillus  species that exhibit a sexual cycle the overwhelming majority in nature are  homothallic  (self-fertilizing). [ 35 ]   Selfing  in the homothallic fungus  Aspergillus nidulans  involves activation of the same mating pathways characteristic of sex in outcrossing species, i.e. self-fertilization does not bypass required pathways for outcrossing sex but instead requires activation of these pathways within a single individual. [ 36 ]   Fusion of haploid nuclei occurs within reproductive structures termed  cleistothecia , in which the diploid zygote undergoes meiotic divisions to yield haploid  ascospores .


Protozoa  are unicellular organisms, which have nuclei, and ultramicroscopic cellular bodies within their cytoplasm. [ 9 ]   One particular aspect of protozoa that are of interest to human geneticists are their  flagella , which are very similar to human  sperm  flagella.


Studies of  Paramecium  have contributed to our understanding of the function of meiosis. Like all  ciliates ,  Paramecium  has a  polyploid   macronucleus , and one or more  diploid   micronuclei . The  macronucleus  controls non-reproductive cell functions, expressing the genes needed for daily functioning. The  micronucleus  is the generative, or  germline  nucleus, containing the genetic material that is passed along from one generation to the next. [ 37 ]


In the asexual fission phase of growth, during which cell divisions occur by  mitosis  rather than  meiosis , clonal aging occurs leading to a gradual loss of vitality. In some species, such as the well studied  Paramecium tetraurelia , the asexual line of clonally aging paramecia loses vitality and expires after about 200 fissions if the cells fail to undergo meiosis followed by either autogamy (self-fertilization) or conjugation (outcrossing) (see  aging in  Paramecium ). DNA damage increases dramatically during successive clonal cell divisions and is a likely cause of clonal aging in  P. tetraurelia . [ 38 ] [ 39 ] [ 40 ]


When clonally aged  P. tetraurelia  are stimulated to undergo meiosis in association with either  autogamy  or  conjugation , the progeny are rejuvenated, and are able to have many more mitotic binary fission divisions. During either of these processes the micronuclei of the cell(s) undergo meiosis, the old macronucleus disintegrates and a new macronucleus is formed by replication of the micronuclear DNA that had recently undergone meiosis. There is apparently little, if any, DNA damage in the new macronucleus, suggesting that rejuvenation is associated with the repair of these damages in the micronucleus during meiosis. [ citation needed ]


Viruses  are  capsid -encoding organisms composed of proteins and nucleic acids that can self-assemble after replication in a host cell using the host's replication machinery. [ 41 ]  There is a disagreement in science about whether  viruses  are living due to their lack of  ribosomes . [ 41 ]  Comprehending the viral genome is important not only for studies in genetics but also for understanding their pathogenic properties. [ 42 ]


Many types of virus are capable of genetic recombination.  When two or more individual viruses of the same type infect a cell, their genomes may recombine with each other to produce recombinant virus progeny.  Both DNA and RNA viruses can undergo recombination.
When two or more viruses, each containing lethal genomic damage infect the same host cell, the virus genomes often can pair with each other and undergo homologous recombinational repair to produce viable progeny. [ 43 ] [ 44 ]   This process is known as multiplicity reactivation. [ 43 ] [ 45 ]  Enzymes employed in multiplicity reactivation are functionally homologous to enzymes employed in bacterial and eukaryotic recombinational repair.  Multiplicity reactivation has been found to occur with pathogenic viruses including influenza virus, HIV-1, adenovirus simian virus 40, vaccinia virus, reovirus, poliovirus and herpes simplex virus as well as numerous Bacteriophages. [ 45 ]


Any living organism can contract a virus by giving parasites the opportunity to grow. Parasites feed on the nutrients of another organism which allows the virus to thrive.  Once the human body detects a virus, it then creates fighter cells that attack the parasite/virus; literally, causing a war within the body. [ 46 ]   A virus can affect any part of the body causing a wide range of illnesses such as the flu, the common cold, and sexually transmitted diseases. [ 46 ]  The flu is an airborne virus that travels through tiny droplets and is formally known as Influenza. Parasites travel through the air and attack the human respiratory system.  People that are initially infected with this virus pass infection on by normal day to day activity such as talking and sneezing. When a person comes in contact with the virus, unlike the common cold, the flu virus affects people almost immediately. Symptoms of this virus are very similar to the common cold but much worse. Body aches, sore throat, headache, cold sweats, muscle aches and fatigue are among the many symptoms accompanied by the virus. [ 47 ]  A viral infection in the upper respiratory tract results in the common cold. [ 48 ]  With symptoms like sore throat, sneezing, small fever, and a cough, the common cold is usually harmless and tends to clear up within a week or so. The common cold is also a virus that is spread through the air but can also be passed through direct contact. This infection takes a few days to develop symptoms; it is a gradual process unlike the flu. [ 48 ]


Microbes are ideally suited for  biochemical  and  genetics  studies and have made huge contributions to these fields of science such as the demonstration that DNA is the genetic material, [ 49 ] [ 50 ]  that the gene has a simple linear structure, [ 51 ]  that the genetic code is a triplet code, [ 52 ]  and that gene expression is regulated by specific genetic processes. [ 53 ]   Jacques Monod  and  François Jacob  used  Escherichia coli , a type of bacteria, in order to develop the  operon  model of  gene expression , which lay down the basis of gene expression and regulation. [ 54 ]   Furthermore, the  hereditary  processes of single-celled eukaryotic microorganisms are similar to those in multi-cellular organisms allowing researchers to gather information on this process as well. [ 55 ]  Another bacterium which has greatly contributed to the field of  genetics  is  Thermus aquaticus , which  is a bacterium that tolerates high temperatures. From this microbe scientists isolated the enzyme  Taq polymerase , which is now used in the powerful experimental technique,  Polymerase chain reaction (PCR). [ 56 ]  Additionally the development of  recombinant DNA technology  through the use of bacteria has led to the birth of modern  genetic engineering  and  biotechnology . [ 9 ]


Using microbes, protocols were developed to insert genes into bacterial  plasmids , taking advantage of their fast reproduction, to make  biofactories  for the gene of interest. Such genetically engineered bacteria can produce  pharmaceuticals  such as  insulin ,  human growth hormone ,  interferons  and  blood clotting factors . [ 9 ]  These biofactories are typically much cheaper to operate and maintain than the alternative procedures of producing pharmaceuticals. They're like millions of tiny pharmaceutical machines that only require basic raw materials and the right environment to produce a large amount of product. The utilization of incorporating the human insulin gene alone has had profound impacts on the medical industry. It is thought that biofactories might be the ultimate key in reducing the price of expensive life saving pharmaceutical compounds.


Microbes synthesize a variety of enzymes for industrial applications, such as fermented foods, laboratory test reagents, dairy products (such as  renin ), and even in clothing (such as  Trichoderma  fungus whose enzyme is used to give jeans a stone washed appearance). [ 9 ]


There is currently potential for microbes to be used as an alternative for petroleum-based surfactants. Microbial surfactants would still have the same kind of  hydrophillic  and  hydrophobic  functional groups as their petroleum-based counterparts, but they have numerous advantages over their competition. In comparison, microbial  amphiphillic  compounds have robust a tendency to stay functional in extreme environments such as areas with high heat or extreme ph. all while being biodegradable and less toxic to the environment. This efficient and cheap method of production could be the solution to the ever increasing global consumption of surfactants. Ironically, the application for bio-based surfactants with the most demand is the oil industry which uses surfactants in general production as well as development of specific oil compositions. [ 57 ]


Microbes are an abundant source of  lipases  which have a wide variety of industrial and consumer applications.  Enzymes  perform a wide variety of functions inside the cells of living things, so it only makes sense that we can use them for similar purposes on a larger scale. Microbial enzymes are typically preferred for mass production due to the wide variety of functions available and their ability to be mass produced. Plant and animal enzymes are typically too expensive to be mass-produced, however this is not always the case. Especially in plants. Industrial applications of lipases generally include the enzyme as a more efficient and cost-effective catalyst in the production of commercially valuable chemicals from fats and oils, because they are able to retain their specific properties in mild easy to maintain conditions and work at an increased rate. Other already successful applications of lipolytic enzymes include the production of biofuels, polymers, non-stereoisomeric pharmaceuticals, agricultural compounds, and flavor-enhancing compounds. [ 58 ]


In regards to industrial optimization, the benefit of the biofactory method of production is the ability to direct optimization by means of directed evolution. The efficiency and specificity of production will increase over time by imposing artificial selection. This method of improving efficiency is nothing new in agriculture, but it's a relatively new concept in industrial production. It is thought that this method will be far superior to conventional industrial methods because you have optimization on multiple fronts. The first front being that the microorganisms that make up biofactories can be evolved to our needs. The second front being the conventional method of optimization brought about by the integration of advancing technologies. This combination of conventional and biological advancement is just now becoming utilized and provides a virtually limitless number of applications. [ 59 ]


Animal Genetics  is a bi-monthly  scientific journal  published by the  Wiley-Blackwell  on behalf of the  International Society for Animal Genetics .


The  impact factor  of  Animal Genetics  is  2.605 (2009) making the journal number 9, out of 50, in the Thomson Reuters ISI "Agriculture, Dairy & Animal Science" category.


Animal Genetics  publishes research on  immunogenetics ,  molecular genetics  and  functional genomics  of economically important and domesticated animals.  Publications include the study of variability at gene and protein levels, mapping of  gene , traits and  QTLs , associations between genes and traits, genetic diversity, and characterization of gene expression and control.


All organisms in the Kingdom Animalia are multicellular heterotroph's that are also eukaryotes.


The  Annual Review of Genetics  is an annual  peer-reviewed   scientific review journal  published by  Annual Reviews . It was established in 1967 and covers all topics related to the genetics of  viruses ,  bacteria ,  fungi , plants, and animals, including  humans . The current  editor  is  Tatjana Piotrowski . [ 2 ]  As of 2024,  Journal Citation Reports  gives the journal a 2023  impact factor  of 8.7, ranking it eleventh out of 191 journals in the category "Genetics & Heredity". [ 1 ]  As of 2023, it is being published as  open access , under the  Subscribe to Open  model. [ 3 ]


In 1965, the nonprofit publisher  Annual Reviews  surveyed geneticists to determine if there was a need for an annual journal that published  review articles  about recent developments in the field of genetics. Responses to the survey were favorable, with the first volume of the  Annual Review of Genetics  published two years later in 1967. [ 4 ]  Its inaugural  editor  was  Herschel L. Roman . [ 5 ]  As of 2020, it was published both in print and electronically. [ 6 ]


It defines its scope as covering various aspects of  genetics , including  molecular ,  cell , and  developmental  biology;  behavioral genetics ,  population genetics ,  chromosome  structure and transmission,  gene  function and  expression ,  mutation  and  DNA repair ,  genomics , and  immunogenetics . Various organisms are considered, including  viruses ,  bacteria ,  fungi ,  plants , and  animals . [ 7 ]   It is  abstracted and indexed  in  Scopus ,  Science Citation Index Expanded ,  MEDLINE ,  Embase , and  Academic Search , among others. [ 8 ]


The  Annual Review of Genetics  is helmed by the  editor  or the co-editors. The editor is assisted by the editorial committee, which includes associate editors, regular members, and occasionally guest editors. Guest members participate at the invitation of the editor, and serve terms of one year. All other members of the editorial committee are appointed by the Annual Reviews board of directors and serve five-year terms. The editorial committee determines which topics should be included in each volume and solicits reviews from qualified authors. [ 9 ]  Unsolicited manuscripts are not accepted.  Peer review  of accepted manuscripts is undertaken by the editorial committee. [ 10 ]


Dates indicate publication years in which someone was credited as a lead editor or co-editor of a journal volume. The planning process for a volume begins well before the volume appears, so appointment to the position of lead editor generally occurred prior to the first year shown here. An editor who has retired or died may be credited as a lead editor of a volume that they helped to plan, even if it is published after their retirement or death.


As of 2022, the editorial committee consists of the editor and the following members: [ 21 ]


The  Atlas of Genetics and Cytogenetics in Oncology and Haematology , created in 1997 by  Jean-Loup Huret  (with bioinformatics by Philippe Dessen) is a collection of resources on  genes ,  chromosomes anomalies ,  leukemias ,  solid tumours , and  cancer -prone diseases. The project is accessible through Internet and is made of encyclopedic-style files, as well as traditional overviews, links towards websites and databases devoted to cancer and/or genetics, case reports in  haematology . It also encompasses teaching items in various languages. [ 1 ]


Starting first from cytogenetics in the nineteens, the Atlas now combines different types of knowledge in a single web site: genes and their function, cell biology (ex: Apoptosis), [ 2 ]  pathological data, diseases and their clinical implications, cytogenetics, but also medical genetics, with hereditary disorders associated with an increased risk of cancer. This gives a wider and more global view of cancer genetics, while these data are usually dispersed. [ 3 ]  It includes a large iconography of about 35,000 images. Dan van Dyke said "This is one stop shopping that unifies cancer genetics information", and Lidia Larizza said that the Atlas was an "interdisciplinary resource".  Felix Mitelman  said "This systematic collection of cytogenetic and genetic aberrations (…) the molecular outcome (…) and the clinical consequences (….) has grown into a truly monumental encyclopedic work of great importance";  Janet Rowley  said: "In the future I will undoubtedly rely on your Website rather than trying to keep up with the literature myself" [ 4 ]


The Atlas is part of the  genome project  and participates in research on  cancer epidemiology . The Atlas is accessed by: 1- researchers in  cytogenetics ,  molecular biology ,  cell biology ; 2- clinicians, haematologists, cytogeneticists, pathologists, from the university hospitals, indeed, but also from general hospitals where the Atlas is one of the rare free resources. Junior doctors in haematology or oncology, are also most receptive to the Atlas that they see as a training and educational tool; 3-Students in medicine and life sciences. [ 5 ]


In 2017, it contains review articles on 1,500 genes, 700 papers on leukemias, 220 on solid tumors, and 110 on hereditary disease with a cancer-prone condition and 110 "Deep Insights" on related subjects, 40,000 internal links and 730,000 external links. This represents 45,000 "web pages" (i.e. about 200,000 printed pages). More than 3,300 authors have/are contributing (1 130 North-American, 400 French, 300 Italian, 200 Japanese, 180 Spanish, 170 German, 160 English, 140 Chinese, etc...) . [ 6 ]  It includes an iconography of about 35,000 images.


In 2018, Jesús María Hernández Rivas (Salamanca, Spain) and Paola Dal Cin (Boston, Massachusetts) joined Jean-Loup Huret as Co-Editors in Chief, and in April 2021 Alessandro Beghini (Milano, Italy) and João Agostinho Machado-Neto (São Paulo, Brazil) replace Jean-Loup Huret. "After 25 years building the Atlas day after day, Jean-Loup Huret and Philippe Dessen will take a little rest", as is said on the web site. [ 7 ]


The Atlas is also published as a scientific journal by CNRS, [ 8 ]  and is referenced by  Scopus  et  Embase .
The Atlas is financially supported by scientific societies, charities and individual donations. More data is available from the site of the association in charge of the Atlas. [ 9 ]


Biochemical Genetics  is a bimonthly  peer-reviewed   scientific journal  covering  molecular biology  as it relates to  genetics . It was established in 1967 and is published by  Springer Science+Business Media . The  editor-in-chief  is Luís Filipe Dias e Silva ( University of the Azores ). According to the  Journal Citation Reports , the journal has a 2021  impact factor  of 2.220. [ 1 ]


This article about a  molecular  and  cell biology   journal  is a  stub . You can help Wikipedia by  expanding it .


BMC Genomics  is an  open-access   scientific  journal covering all areas of  genomics  and  proteomics . The journal was established in 2000 and is published by  BioMed Central . Its 2022  impact factor  is 4.4. [ 1 ]


The journal is indexed in  PubMed , PubMed Central,  MEDLINE ,  BIOSIS Previews ,  EMBASE ,  Scopus ,  Zoological Record , and other indexing services. [ 2 ]


Comparative Cytogenetics  is a  peer-reviewed   open access   scientific journal  covering plant and animal  cytogenetics ,  karyosystematics , and  molecular systematics . It was established in 2007 by the Zoological Institute of the  Russian Academy of Sciences . In 2009 it switched to   Pensoft Publishers . [ 1 ]  The  editors-in-chief  are Valentina G. Kuznetsova and Ilya A. Gavrilov-Zimin (Russian Academy of Science).


The journal is abstracted and indexed in: [ 2 ]


According to the  Journal Citation Reports , the journal has a 2013  impact factor  of 1.211. [ 3 ]