I heard from a lecture of major occurrance of Down's syndrome in female, but when I check for verification I found male to female ratio at 1.3 to 1. So maybe something wrong there, but this leads me to think about why one sex will be more susceptible to some genetic disease like chromosome 18 trisomy. Any suggestion?

I would think it would some how be related to the y chromosome it being the main difference between male and female genes but that doesn't seem to make sense, and that difference is awfully high to just be a coincidence. But if i had to take a guess i would say something y chromosome related.

 

p.s. i believe down syndrome is caused by chromosome 21 trisomy