Fibrinogen Baltimore IV: congenital dysfibrinogenemia with delayed fibrin monomer polymerization

A congenital dysfibrinogenemia, fibrinogen Baltimore IV, has been found in a 56-year-old Caucasian man. Clinical laboratory studies disclosed a slightly prolonged prothrombin time, but were otherwise unremarkable. Release of fibrinopeptides by thrombin occurs normally, as does ligation of the fibrin polymer by Factor XIII. Approximately half of the isolated fibrin monomers polymerize normally, but the remainder polymerize at about 2% of the initial rate. The functional defect is thus limited to a decrease in the rate of fibrin monomer polymerization.