Hereditary combined deficiency of clotting factors V and VIII with involvement of von Willebrand factor.

A family is described in which two brothers, with a significant haemorrhagic disorder, are affected by combined factor V/VIII deficiency. In one of these patients an abnormal decrease of von Willebrand factor was also observed. Family studies suggest that both of the brothers are homozygous for a recessive gene. Normal laboratory results were found in eight other family members although seven of them had reported a mild bleeding tendency. The results indicate that hereditary combined factor V/VIII deficiency is a heterogeneous disorder and that defects of von Willebrand factor might be involved in the aetiology of the disease in some families.