Which of the following statement(s) is/are true concerning hemophilia A?

a. Hemophilia A is inherited as a sex-linked recessive deficiency of factor VIII

d. Spontaneous bleeding is unusual with factor VIII levels greater than 10% of normal

Hemophilia A is inherited as a sex-linked recessive deficiency of factor VIII although 0% of cases are secondary to spontaneous mutation. The incidence of this abnormality is approximately 1/10,000 births. Laboratory screening tests usually reveal a prolongation of an aPTT but normal prothrombin time (PT), thrombin clotting time (TCT) and platelet aggregation testing. The minimum level of VIII required for hemostasis is 30% for minor bleeding, whereas spontaneous bleeding is unusual with factor levels greater than 5 to 10% of normal. In severe genetic deficiency states however, factor levels as low as 1% have been noted and patients are at risk for spontaneous bleeding.