FAMILY SURVEY Hemophilia A/B is a group of sex-linked recessive inherited bleeding disorders. The defective gene is located on the X chromosome and is carried by the female (mother) and inherited to the male (son) for the onset of the disease. Therefore, when diagnosing hemophilia A/B, a family lineage survey must be conducted, and about 2/3 of patients have a positive family history. The results of a typical hemophilia A/B family lineage survey are shown in the figure. An example would be to say that a carrier mother married to a normal father has a 50/50 chance of having a son with hemophilia, having a daughter who will not develop the disease, but has a 50/50 chance of being a carrier carrying the disease-causing gene. If a sick father marries a normal mother, the sons will all be normal, healthy babies, and if daughters are born, they will all be carriers. Therefore, families with a family history of hemophilia should consult with the relevant genetic disease counseling agency or go to the local hemophilia clinic to ensure that hemophilia is not passed on to the next generation and that the offspring have a healthy body.