So I’m aware there’s other possible abnormalities of other chromosomes such as ring shaped chromosome 20, but I’m wondering why down syndrome with chromosome 21 is so relatively common? What about it makes it more likely to get an extra/abnormality?
Edit: Seems to be equally common and it’s simply that because chromosome 21 doesn’t have very many “important” genes so babies with down syndrome can still survive, while the others will always miscarry or die shortly after birth. Confirm? thanks
In: Biology
Just to add one additional piece of information: The chromosomes are numbered by length, so 1 is the longest and 22 is the shortest (X/Y are separate). That means 21 is the second-shortest non-sex chromosome. It’s not coincidence that we find the one well-survivable extra chromosome towards the end of the list.
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