this post was submitted on 17 Jun 2025
178 points (99.4% liked)

Biology

2412 readers
70 users here now

This is a general community to discuss of all things related to biology!

For a more specific community about asking questions to biologists, you can also visit:

/c/askbiologists@lemmy.world

founded 3 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
[–] Ledericas@lemm.ee 18 points 3 weeks ago (1 children)

works while as the egg, but not as grown human.

[–] protist@mander.xyz 10 points 3 weeks ago (2 children)

This is not true on multiple levels. One of the benefits of the Crispr technique is it can be used in vivo, so this sort of treatment will potentially be able to be used at any point in an individual's life. But also, trisomy-21 isn't present in sperm or eggs, it's a mistake in cell division early in fetal development, so applying this technique to an egg would have no purpose or effect.

[–] dondelelcaro@lemmy.world 9 points 3 weeks ago (1 children)

trisomy-21 isn't present in sperm or eggs, it's a mistake in cell division early in fetal development

This is incorrect. Non-disjunction (where chromosomes incorrectly separate) typically happens during the formation of egg or sperm. (We know this because most everyone with down syndrome has three different chromosome 21 instead of two identical copies of one chromosome.)

[–] protist@mander.xyz 8 points 3 weeks 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.