Hereditary factor VII and IX deficiencies in a large kindred.

A large kindred with combined deficiencies of factors VII and IX is presented. The deficiencies appeared to be independent and the data were not consistent with a diagnosis of haemophilia BM. The identification of mildly affected family members, including carriers of haemophilia B and heterozygotes for factor-VII deficiency, was facilitated by comparison with the 95% confidence interval of an age- and sex-matched control population. The bleeding patterns were those of mild to moderate haemophilia B and did not appear to have been modified by the presence of factor-VII deficiency.