Downs Syndrome isn’t a disease that is happens because the mother or father is a “carrier” of it. It happens at conception, when something goes awry genetically and the chromosomes get screwed up. Although the chances increase as the mother ages, a woman of any age could have a baby with Down Syndrome. A non-pregnant woman, or a man, could be tested to see if she or he is a carrier for, say, cystic fibrosis, but no non-pregnant woman, and no man, could be tested to see whether she or he is a carrier for Downs Syndrome.
You may not have noticed that my post,was satirical. The point was that humans are “carriers” of humanity. Get rid of humankind, and presto change-o, no more human problems.
Downs Syndrome isn’t a disease that is happens because the mother or father is a “carrier” of it. It happens at conception, when something goes awry genetically and the chromosomes get screwed up.
Down Syndrome is one of the few aneuploidies in a gamete (not an embryo, but in the egg or more rarely the sperm) that is lucky enough to mostly result in life. An aneuploid egg does not have the chromosomes correct so will not result in a baby at all, 95% of the time. Down Syndrome does allow life, though some born with it do have a much shorter lifespan. There can be heart defects and other serious problems.
So Down doesn’t happen at conception. The egg used to create that person was already “bad.” This is the reason older women have a higher rate of Down Syndrome kids. As we age, egg quality diminishes in the eggs in our body. They were all made when the woman herself was in uterus and they have a shelf life.
When the woman is older, late 30s, half or more of her eggs might be aneuploid. Most of the time these bad eggs will either not make an embryo or will make one but it won’t divide properly and will die within 12 weeks. The most common kind of early miscarriage.