Anonymous wrote:
Anonymous wrote:Saudi Arabia, high incidence of inherited conditions.
Yep. Saudi has very high Down Syndrome rates. And around two-thirds of marriages are blood relatives.
PP from the hemophilia correction here. More basic genetics knowledge is really needed on this thread!
Down syndrome is not heritable in almost all cases- it is a trisomy (ie triplicate) of one of the chromosomes. A trisomy occurs spontaneously at a very low rate after cell division. There are a few rare genes that can increase your risk of having a child with Down syndrome (because you tend to produce such trisomies more often) but those are believed to be implicated in only a tiny percentage (<5%) of Down syndrome cases.
Also, from another thread a recessive gene cannot become dominant. It is that you get two copies of the recessive gene, one from each parent, and then you start to express the recessive trait. Inbreeding increases the chance that you will get two copes of a mutant or unusual gene because both your parents originally got it from the same place.
This thread is a walking ad for why smart people should also study STEM fields. Educate your children first.
(A STEM PhD who is not even a biologist but has learned how to think about science)