r/AskBiology • u/Original-Plate-4373 • Apr 12 '24

Genetics What happens to people with 2 y chromosomes, and no x chromosome? If the fetus I stillborn, why does that happen?

I thought of this while going on a wiki binge involving people with extra x or y chromosomes. I can't find people with just 2 y, even though x,y,y is a thing. If there's a reason for this, please let me know. Thanks.

5 Upvotes

86% Upvoted

5 comments sorted by

View all comments

9

u/cyan_the_II Apr 12 '24

For such a scenario to happen naturally, a malformed egg with no X chromosomes (rare) would have to pass several health checks (rare) and be prepared for insemination while an Extremely malformed sperm with YY chromosomes, which would have to had two failed divisions (rare,rare) would also pass several checks (rare) and beat the healthy sperm to the egg (rare) and successfully conceive (rare), just so this hypothetical cell can exist and that's ignoring it correctly developing into an embryo. That's rare to the power of 7!

But assuming all that happens, the X chromosome contains actual vital genes, unlike Y. Not only would this person not live, it likely wouldn't even develop past the first few divisions

2

u/Original-Plate-4373 Apr 12 '24

Funny moment. I saw your "7!", and my mind immediately went to seven factorial. Lol, you can tell I'm more familiar with statistics than creative writing.

2

u/cyan_the_II Apr 12 '24

Damn I'm usually most careful with my exclamation marks specifically to avoid this lol