Haemophilia Gene Inheritance

What are the chances that a hemophiliac male and an unaffected, non-carrier female could have a baby that is a hemophiliac male?

It is very rare because the father contributes the Y chromosome to the child, which makes him a boy. Even if the father is hemophiliac when he has a wife who is a non-carrier, it is almost impossible for the (Cutter, 2011). If the child were a girl, it would have been different. In this case, since the male parent give half of the chromosomes, which determine whether it is a girl or a boy. Girls, in this case, would get the X chromosome from the man either with or without the gene. The girls, in this case, will not have hemophilia but will be carriers of the hemophiliac gene with their mother who does not have them donating a dominant gene to the child. The gene can only be carried on the X chromosome gene, and boys usually obtain the X chromosome from their mothers.

Fathers, in this case, have the X and Y chromosome while the mothers have X and X chromosomes. The chances of women carriers transferring their hemophilia to their children especially boys, in this case, is fifty percent (Starr & McMillan, 2014). On the other hand, the mother, in this case, does not have hemophilia and is not a carrier. Therefore, the mother, who is a noncarrier, gives the X chromosome, which does not have the hemophilia gene hence the boy will not suffer from hemophilia. As seen from above, even though the father is hemophilia he gives the Y chromosome to the boy, which lacks the hemophilia gene. Therefore the boy has zero chances of getting hemophilia from a father with hemophilia and a mother who does not have hemophilia and is a non-carrier.

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