Question

A man is stricken with a type of hemophilia that is an X-linked recessive genetic disorder. His mother is a carrier of the disease, but his father is not a carrier and is not affected by the disease. The man has four daughters. What percentage of his daughters will MOST LIKELY have the gene for hemophilia?
0, 10, 50, or 100%

Answer 1

Hemophilia A is an X-linked recessive disease caused by a lack of a coagulant, or blood clotting agent, called factor VIII (factor 8). This is caused by a mutation in a gene on the X chromosome called F8. If a father is affected, his daughters will be carriers of hemophilia A and his sons will be unaffected. If a mother is an unaffected carrier, each daughter has a 1 in 2 chance (i.e., 50%) of being an unaffected carrier and each son has a 1 in 2 chance (i.e., 50%) of being affected with hemophilia A.