Someone once told me that if a man has the XYY chromosome then he will be sterile. Is this true?
827633
They are usually fertile and lead ordinary lives as adults. \n\nXYY syndrome  males inherit an extra Y chromosome--their genotype is XYY.  As adults, these "super-males" are usually tall (above 6 feet) and generally appear and act normal.  However, they produce high levels of testosterone.  During adolescence, they often are slender, have severe facial acne, and are poorly coordinated.  They are usually fertile and lead ordinary lives as adults.  Many, if not most, are unaware that they have a chromosomal abnormality.  The frequency of XYY syndrome is not certain due to statistical differences between different studies.  It may be as common as 1 in 900 male births to as rare as 1 in 1500 or even 1 in 2,000.
372234
Taken from Wikipedia (see link below)...\n\nXYY syndrome is also called Jacob's Syndrome, XYY-trisomy, 47,XYY aneuploidy, or Supermale syndrome.\n\nFirst case\nThe first published report of a man with a 47,XYY chromosome constitution was by Dr. Avery A. Sandberg, et al. in 1961. It was an incidental finding in a normal 44-year-old, 6 ft. [183 cm] tall man of average intelligence.\n\nPhysical traits\nXYY syndrome typically causes no unusual physical features or medical problems. Males with this syndrome may be slightly taller than average and are typically a few centimeters taller than their father and siblings.\n\nSkeletal malformations may also accompany XYY syndrome at a higher rate than in the general population. Severe facial acne has occasionally been reported, but dermatologists specializing in acne (Plewig & Kligman, 2000) now doubt the existence of a relationship with XYY. Several other physical characteristics, including large hands and feet, have been associated (although not definitively) with XYY syndrome. Any physical characteristics, however, are usually so slight that they are insufficient evidence to suggest a diagnosis.\n\nMost males with XYY syndrome have normal sexual development and are able to conceive children.\n\nSince there are no distinct physical characteristics, the condition usually is only detected during genetic analysis for other reasons.\n\nBehavioral characteristics\nXYY boys have an increased risk of minor speech and motor skill delays and learning disabilities with roughly half requiring some special education intervention. Behavior problems are common, but are not unique to XYY boys and are managed no differently than in XY boys. There have been suggestions of elevated frequency of XYY genotype in inmates and delinquents. A common myth is that the Y Chromosome (male sex chromosome) adds to the aggression and antisocial behavior of people who have this syndrome. No clear evidence exists of it leading to aggression. However, scientists have noticed that an abnormal amount of prison inmates in comparrison to the general population have the XYY chromosome (still some think this is no proof of a link).\n\nCause and prevalence\nXYY syndrome is not inherited, but usually occurs as a random event during the formation of sperm cells. An error in cell division called nondisjunction can result in sperm cells with an extra copy of the Y chromosome. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra Y chromosome in each of the body's cells. In some cases, the addition of an extra Y chromosome occurs as an accident during cell division in early fetal development.\n\nThe incidence of this condition is approximately one in 850 males.\n\n\nThe 48, XXYY (male) syndrome occurs 1 in 17,000 births and is also considered to be a variation of Klinefelter's syndrome. There have been limited studies on XXYY, but people who have XXYY are mostly normal.
1092146
Yes. Fragile X is carried by females but affects male offspring. If you are a woman from a family where males have fragile X make sure you have genetic counselling before going ahead with a family. If fragile x is a possibility often the best way forward is to have a donated egg implant which can be fertilized by your partner. The first port of call should be your GP before you consider having a family. DO NOT BE FOBBED OFF WITH ADVICE LIKE "IT WILL PROBABLY BE OK" as some GP's are not up to speed with this. Ensure you are referred to your local hospital first.
477743
Why all these people are saying its 50/50 I have no idea.  It certainly is NOT 50/50, the chance varies for every individual.  Some males have more sperm with the X chromosome and some have more sperm with the Y chromosome.  Very few, if any, males have an exact 50/50 ratio.
581875
C... a boy would have XY chromosomes and a female would have XX chromosomes.  Y is always smaller than X.
301931
umm, though i'm not sure what the question really says- i think you are asking about genetic diseases involved with chromosome number, if i'm right the following stands, if not then ignore it. \nif you have less or more chromosomes than 46 you will not survive far past fertilization, at least thats what i understand- either that, or you would be a different species- unable to produce a fertile offspring with a human.\n\nHowever there is a lot of confusion around Down's syndrome. This is caused by non-disjunction of chromosomes during meiosis, and creates trisomy genotypes on chromosome 21. \n\nTrisomy and non-disjunction can also occur on chromosome 17- causing another disease, which i have momentarily forgotten the name of. sorry.
890925
Men typically have one X chromosome and one Y chromosome in each diploid cell of their bodies. Women typically have two X chromosomes.
621951
all normal males are XY.  all normal females are XX.  the female always donates 1 X chromosome to the offspring.  the male donates either an X or a Y to the offspring (50% chance of each event).  If the male donates an X, the offspring will be XX and female.  if the male donates a Y, the offspring will be XY and male.
21663
Ok so I heard that there is slight possibility the vasectomy fails....but it's a VERY slight chance of it happening. If you feel that there is some question, get a DNA test.
491786
You can improve your chances. Sperm determine sex. A Y chromosome is lighter than an X chromosome. So, if you ultra-centrifuge sperm, the 'males' will be a higher fraction than the heavier 'females'. \n\nIt's done in animals all the time. It's not 100%, but it sure increases the odds.
14261
it is in most cases.\nthe inheritence if extra 23rd x chromosome leads to a homosexual offspring.\nbut inmany cases it is by will.
453082
It can happen to anybody - check with your doctor to find out if yours is hemophilia.  There are other blood disorders as well, such as sickle-cell anemia.  That's a disorder where the red bood cells change shape and can't carry oxygen as well as they should be able to.\n\nsoaplady99ca is incorrect in saying that it only effects men.  If the father of a child has the trait, and the mother of a child is a carrier, and the mother passes the chromosome with the trait, then a female can get it - X(defect)X(defect) would result in a female with the defect.
617905
First of all we have 23 pairs of chromosomes (or 46 chromosomes), and monkeys have  22 pairs of chromosomes. Big deal right? WRONG. When humans make gametes (sperm and egg) each gamete contains a one copy of the hosts DNA, therefore each gamate only contains 23 chromosomes. When the sperm reaches the egg they combine together (zygote) to from a cell that has 46 chromosomes. Any deviation from this number makes the an embryo inviable. ( we wont get into ploidy or trisomys here). Therefore if a human and an ape mated, the chromosome count coming from the human would be 23 and the money would be 22 making the chimera have 45 chromosomes. First of all essential genetic coding inforemation is lost. (AN ENTIRE CHROMOSOME IS MISSING), you have changed the specie. You have created an alleuploidy. (only viable with some plants). The chromosomes in each species are of different sizes. This totaly screws up the cellular functions and inhibits a proteins job. They would not be able to reproduce. And please do not get me started on Mullers moprhs in terms of loss of genetic information, regarding epistasis, incomplete dominance etc.... All you need to know is it would be inviable because the chromosomes are of different numbers, and the chromsome sizes are different.
552790
"At least 97% of men with CF are sterile due to congenital bilateral aplasia of the vas deferens (CBAVD), an absence of the vas deferens. There are new technologies that are offering hope to men with CF who desire to father a child since sperm is present. This would involve aspiration and In vitro fertilization. Having a discussion with a fertility specialist would be helpful in those cases. Additionally, men who do not have cystic fibrosis but are born with congenital absence of the vas deferens have an increased risk being carriers of the CF gene.\n\nWomen with CF may also have impaired fertility, as thicker cervical mucus may prevent sperm from entering the uterus and thus reduce the likelihood of unassisted conception"
663414
No, the number of chromosomes in the two is different so it would not create a baby.
382442
Yes, the Y-chromosome is shrinking.\n\nThe reason is due to recombination. Recombination increases the effectiveness of selection, meaning that more "good" mutations are kept and more "bad" mutations are removed.\n\nThe X-chromosome can recombine during meiosis, but the Y-chromosome cannot. Therefore, the Y-chromosomes cannot repair "bad" mutations. These mutations build up on the Y-chromosome over time. Some of these mutations can cause the Y-chromosome to shorten. In some species, like Drosophila, the Y-chromosome is no longer present! Females are XX while males simply have an X chromosome!
46461
In most instances, human offspring with differing numbers of chromosomes are miscarried before any progression toward birth.  In cases where there are extra chromosomes such as trisomy 21 where there is an extra chromosome on the 21st pair (47 total), the pregnancy may be carried to term and the fetus has a syndrome known as down sydrome.  Kleinfelter syndrome there is an additional X chromosome in males producing XXY.  There are also turners sydrome in females where they are lacking an X chromosome (45), they fail to develop secondary sex characteristics and are also sterile because their sex organs do not mature.  This is only an example of some chromosomal abnormalities.  You can look up more on the web.