Congenital factor V deficiency. A family study

A 14-month-old girl suffering from a heavy bleeding tendency, caused by a severe isolated congenital factor V deficiency is described. In this study 56 family members were examined. 10 of them had a factor V level ranging 26-60% of the normal--these were classified as heterozygotes. The case histories of the heterozygotes did not reveal a bleeding tendency. The inheritance of this factor V deficiency is autosomal recessive, with varying expressivity in the heterozygotes.