Generally, the incidence of FVIII inhibitor in hemophilia A patients with severe disease (FVIII:C <1%)and moderate disease (FVIII:C >1% to 5%) is estimated to be 20% and 33%, respectively [1,2,3,4,5,6]; however, differences in the incidence between ethnic groups might be due togenetic differences. The gene discussed is F8; the disease is hemophilia A.