Rare coagulation factor deficiency (RFD) is characterized by a deficiency of factor (F) I, FII, FV, FVII, FX, FXI, FXII, FXIII, or a combined deficiency of FV + FVIII or vitamin K-dependent factors and accounts for approximately 5% of all bleeding disorders. The gene discussed is F5; the disease is hemorrhagic disease.