Why does the occurence of Down syndrome increase with maternal age?
598892
if you're a female human, you're born with all the eggs you'll ever have already made.\n\nthey arrest in meiosis ii, and as eggs mature, they complete meiosis. the longer they're arrested in that state (aka the older you are when the egg finally matures), the higher the chance that chromosome separation will not occur properly.
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.
277848
No clue yet on this one. But leading research is showing that this may be a random event because of chromosome breakage. I would look into telomerase extension if I were you. Most of the time this is bad (Double stranded DNA breaks), but it happens all of the time (but luckily we have a good DNA repair system, I believe there are well over 1000 breaks a day and all we need is 1 for some bad genetic disease)
1089146
I'll stay strictly biochemical, and not consider teliology or evolution, since the previous answerer addressed some of this.\nThough there is a hypothesis that aging and death occur because of damage, oxidative stress, etc, there is actually very little data to support this-in fact, the information we have explicitly argue against this.  Rats, mice, etc, live only 2-3 years, and show cellular degeneration, etc, very similar to that seen in aged humans, and yet are not exposed to greater levels of oxidative stress, or indeed extra stress of any kind, than humans.  If it truly were a matter of stress exclusively, the range of survival times would tend to be much broader than what we see- IN other words, some humans would die of old age at 5 or 6 years old, and some would live to 200-300 years old.  Stress, oxidation, poor diet can indeed influence the age at which we die, but they are not the primary determinants... it is apparent that this is a genetically controlled phenomenon, and that it occured soon after the rise of multi-cellular organisms, and that it varies greatly between species.  There have been some senescence genes found, that are specifically turned on that seem to guide cellular damage-however, it seems as if the greatest portion of the aging process, developmentally, is caused not be production of completely new proteins which end up killing us, but by variations of levels of proteins already expressed- For instance, there are significant decreases throughout life in a number of hormones, including androgens (in men) growth hormone, insulin-like growth factors, various neurotrophic factors, etc- and a concomittant rise in others, especially pro-inflammatory hormones, such as TNFa and certain interleukins.  All of this is genetically and developmentally regulated to a fairly specific time, and is slightly variable depending upon diet, exercise, etc- It is similar to the timing of puberty, which is primarily set as 11-16 years old, but is variable depending on environmental factors.  Outside of specific diseases, puberty will occur between approximately 8 and 18-19 in over 95% of the population, and in 100%  of the population (again, assuming no genetic defect or disease) will have occured by 21 or so.  human death, under the best of circumstances, probably will occur at around 85-90 years.  outside of specific non age related diseases, the range will be around 65-115, which is pretty tight.  The fact that we have *never* observed a mammal that lives forever, the genes that control senescence are likely very tightly connected to genetic programs necessary for survival-so that if an animal is missing the genetic program that controls death, it won't survive embryogenesis to begin with (otherwise, some percentage of mammals would live extremely long-which likely is extraordinarily damaging to the population of that species, and is thus dramatically regulated so it will never occur).\nIt is fairly likely that, within the next 100 years, this genetic control program will be dissected and understood, and then it will be a short time until it will regulatable clinically.  \nDeath is controlled by our genes, which are, in the end, simply biochemical control systems, and which are comprehensible with enough study- Then it becomes a societal decision as to how we should manipulate this.\n*edit* There is interesting observation with telomeres, and about 10 years ago, we thought this might be the hidden secret, but unfortunately, it doesn't appear to be so.  In many immortal, or long-living cells, telomeres play no role, and even in cells in which telomeres are artificially extended, there is still senescence (though it appears to occur somewhat later).  Telomeres are a clock that determines how many times a cell may divide before it enters a "cellular suicide" program, and thus it was thought this was critical to lengthening lifespan-however, most sensescence in mammals does not seem to occur because o
1121908
Yes, It is due to activation of oncogenes or external carcinogenic agents. These genes are present in all higher animals. Development of cancer is one of the related sign of aging also.
190426
Interesting question.  I hadn't even thought of this question yet.  True, there is/are NO definitive cause/s of Autism.  Recent studies studies are showing, however, possible genetic links.  More studies are being done because more and more siblings, of people with Autism, are being born on the spectrum, or with closely related developmental disorders.  These recent studies show changes in ALL chromosomes...not just one as found in other disorders like Downs.  Remember, though, NOTHING definitive at this point.\n\nMy intuition tells me that it is possible for an adult with Autism to have a child who is also on the spectrum.  I see too many families with multiple children on the spectrum.  I see twins who both have it.  There is something genetic...there just has to be.  What are the chances in numbers?  I wish I, or anyone else, could say.  Best of luck!
507203
Because some woman have low  pregnancy hormone  levels and its hard to pick up until their a couple months along in their pregnancies. And have to rely on the blood test to pick them up . I know because i have the same problem.  I hope this helps.
21043
Sure, if a person has an extra copy of Chromosome 21 (trisomy 21) They are mostly likely someone who has Down Syndrome. There are many other instances of extra chromosomeos (Kleinfelder's syndrome, XXY syndrome, etc).
1170133
This happens on occasion. My sister was told that her second and third child was a girl and both ended up being boys (Yeah since it was the first boys in family in 40 years). The only absolutely 100% test is an Amnio centisis. That is when they tast the fluid of the sack to see which chromosomes are there. But relax it happens. I hope this is what you were asking.
220614
Well, in scientific form this is caused by the Mendelian trait, Law of Dominance. One trait (Btwn any of your parents)is more dominant than the other. It can also be caused by sex-linked traits found in the x-chromosome. There are characteristics that the daughter will get that is diff. from the son. It is just normal. I too look more like my dad.
205826
There is no general answer; one would need to know the exact treatment involved, or at least the drug.\n\nHowever, it's unlikely.  Fertility is a complex mix of factors, including some as random as diet and stress, to the obvious such as exposure to radiation.  I am fairly on top of the medical literature and have never heard of a fertility increase being passed on to a daughter via a mother's treatment.\n\nIt's more likely there are other explanations:\n1) you or the father may be younger then they were.  Age has an enormous relation to fertility.\n2) you or the father may be healthier than they were.  Health (and stress and diet) have a relation to fertility.\n3) the father may have higher sperm count/motility than your parents or your husband's parents.\n4) you are experiencing normal statistical variance in pregnancy, but (to you) it seems like it is highly unusual.\n\nand so on.\n\nMy bet, without knowing more, is on #2 or #4.
367295
see the doc. i have a family member that could'nt have kids until she was in her 30's or 40, somethiong like that, but anyway something about her overys, but she finnally had kids after being treat from a doc.
435739
There is a risk of having an unhealthy baby at any age. The risks of having a baby with Down's syndrome or other genetic disorders, for instance, increase over time with the age of the mother, but there are still lots of healthy babies who are born to women in their forties.
623276
Age--having babies--weight loss or gain--I think many factors might contribute to that.
1118943
it may be your hormones changing as you get older things change, my mom went through the same thing and found it just to be stress and aging. she found the best thing that worked was proactive!
51143
could just be age, genetics or vitamin deficency
1180116
I agree with most people in this forum ... you're never too old.   \n\nWomen are often cautioned, however, about planning to have children once they reach their late 30s and hit 40 since the chances of giving birth to a child with a genetic anomaly (ex. Down's Syndrome) increases quite dramatically.  You can still bear a child if you're willing to accept the risk or can adopt and, of course, you can marry at any age you feel like.