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submitted 1 month ago by cm0002@lemmy.world to c/biology@mander.xyz
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[-] protist@mander.xyz 8 points 1 month ago

TIL

  • In the majority of cases, the extra copy of chromosome 21 comes from the mother through the egg.
  • In a small percentage (less than 5%) of cases, the extra copy of chromosome 21 comes from the father through the sperm.
  • In the remaining cases, the error occurs after fertilization, as the embryo grows.
this post was submitted on 17 Jun 2025
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