Please explain x-linked recessive...?

Question

Would someone that is in a x-linked recessive pedigree chart, and is affected be AA or aa? Thanks

Would a female carrier be Aa? can men carrier it?

Answer 1

X means it is on the sex chromosome rather than one of the other chromosomes (which are called autosomes). There are two kinds of sex chromosomes: X and Y. Females are XX, while males are XY. If a trait is recessive, then it means you must have only the recessive copy (male), or two recessive copies if you are a female. Females with only one recessive copy are considered to be a carrier, meaning they could pass on this trait to a child but do not exhibit signs or symptoms of having this trait. I usually when doing a pedigree just write 'X' if it is a normal (unaffected) x-chromosome with reference to that specific trait, and 'Xa' if it is. It doesn't have to be the letter a, I just pick a letter than could represent this specific trait. Thus, you could have a female with XXa meaning they are a carrier, or a female with XX who has both dominant alleles (not a carrier) or a female with XaXa who will demonstrate the recessive trait due to having both copies. If this was an x-linked dominant trait, then being heterozygous or in other words, XXa, would result in expression of this trait, unlike in the case of the recessive gene. For males, since there is only one copy of the X chromosome, if the male inherits the Xa, it will be expressed even with a normal Y. So for males, there is no carrier state, either the male expresses the trait (XaY) or does not express the trait (XY). I hope this helps!

Answer 2

X-linked recessive is a recessive mutation that lays on the X chromosome, also knows as sex-linked

It all depends of the gender. If it's male, then the male has to be ay (assuming that a is the mutation) and a female will have to be aa to be affected. I hope that helps!

Answer 3

If female, it would have to have 2 recessive a's so XaXa

If male, the only X is recessive so XaY