Posted: Nov 08, 2017 4:03 pm
by Calilasseia
No. "Autosomal" means "on chromosomes other than the X any Y chromosomes".

For example, Factor VIII haemophilia is not autosomal, because, bizarrely, the gene for clotting factor VIII resides on the X chromosome (at least in humans). Consequently, factor VIII haemophilia is a sex-linked recessive disease. Women generally don't suffer from this, as they inherit two X chromosomes, and even if one of them carries a defective factor VIII gene, the other usually carries the normal gene, and this is dominantly expressed. However, women inheriting this combination become carriers of the condition.

Men, on the other hand, inherit an X and a Y chromsosome, and there isn't a copy of the factor VIII gene on the Y chromosome. So a man inheriting an X chromosome with a defective factor VIII gene is stuffed, because unlike a woman, he won't have a partner gene overriding the defective one. That's why factor VII haemophilia is seen most frequently in men. Only on the very rare occasion that a woman inherits TWO defective factor VIII genes, one from each parent, will a woman manifest factor VIII haemophilia.

Autosomal chromosomes, of course, are always inherited in pairs, regardless of sex. So there's usually no sex linkage between autosomal recessive genetic disorders, though in some cases, some rather intricate mechanisms can come into play to create a sex bias.

Matters become somewhat more complicated once incomplete dominance or codominance plays a role.