Association of hereditary heparin co-factor II deficiency with thrombosis.

A family was investigated for heparin co-factor II deficiency. Three of the five members examined had had thrombosis and their levels of heparin co-factor II were reduced to 50%. All five members had antithrombin III levels within the normal range. Analysis on crossed immunoelectrophoresis showed no qualitative abnormality of patient heparin co-factor II antigen. Since heparin co-factor II activity and concentration were reduced to the same extent, the deficiency was due to reduced protein synthesis.