I want to ask sth about Haemophilia

Question: Is it just passed through chromosome X?
Answer: Yes. Since it is a sex-linked, X chromosome disorder, affected almost entirely in males

Question: Our is it also passed through chromosome Y?
Answer: No.

Question: I thought an infected chromosome X must pair with an infected chromosome Y in order to affect a boy's health.
Answer: No. Since it is a sex-linked, X chromosome disorder, there will be no affected Y chromosome.

Question: From another知識 thing, it says that abnormal X' with normal X makes a normal girl, who's not a carrier, it that right or wrong.
Answer: Entirely wrong. Girl with an abnormal X' chr. and a normal X chr. manifest normal but herself a carrier, that is, if she marries to a NORMAL husband (normal Y and normal X), there will be give birth to - 1/4 normal girl (X-X), 1/4 normal boy (X-Y), 1/4 carrier girl (X'-X) and an affected boy (X'-Y)


Help this will help you.

It is definitely on chromosome X and absent on chromosome Y. You forgot about boys also have a chromosome X. [Boys are XY, remember?] Instead of two copies, Boys have only 1 copy of chromosome X.
(1) If that's a defective haemophilic gene, he's got it. and 100% pass it on to his children.
(2) If that's a healthy gene, he will not get it, and definitely not pass it on to his children.
Girls have 2 copies of chromosome X [Girls are XX].
(1) So if the girl is lucky enough to have one defective and one healthy gene, the symtoms will not show. She is a carrier. There is a 50% chance she may pass it on to her children.
(2)If she is unlucky enough to have both defective genes on the two chromosomes, then she will also have haemophilia. So instead of carrier, she is a patient. She will 100% pass the gene on to her children.
(3) If she has both healthy genes, there's nothing to worry about.