Fatal Bleeding Caused by Congenital Factor XIII Deficiency and Development of An Inhibitor in a Hispanic Male

We report a case of fatal bleeding in a patient with mild congenital Factor XIII deficiency who also developed an inhibitor that interfered with fibrin stabilization. Plasma Factor XIII circulates as a tetramer composed of two A-chain and two B-chains and is bound to fibrinogen. After thrombin cleaves the A-chain at Arg 37, the B-chain dissociate producing Factor XIIIa. Factor XIIIa catalyzes covalent linkages between the fibrin molecules aligned in the fibrin clot. Factor XIIIa makes the fibrin resistant to disruption by urea and plasmin. Factor XIIIa levels greater than 1 % are needed to covalently stabilize a clot. We studied a 39 year old Hispanic male that presented with altered mental status, headache and a large left frontal parietal hemorrhage. Ultimately, he became non-responsive and was intubated. He had no major bleeding history but did have frequent nosebleeds. Routine blood counts and coagulation laboratory tests were normal. However, a qualitative Factor XIII assay was abnormal and the clot dissolved in 5M Urea. Furthermore, a 1:1 mixing study did not correct the defect suggesting the presence of an inhibitor. A small dose of cryoprecipitate was administered to the patient and this corrected the clot stability defect. Four days later, the defect recurred and 150 ml of cryoprecipitate was administered and despite correction of the fibrin stabilizing abnormality the patient died. Two of his sisters had a history of repeated hemorrhagic miscarriages in Mexico a finding consistent with congenital Factor XIII deficiency. DNA sequencing of the factor XIII a-chain gene was performed from the propositus’ mononuclear cells. A reverse transcription was done using an oligo(dT) 12–18 primer followed by nested PCR amplification and a heterozygous missense mutation was observed at codon 35 (G226T; Val35Leu). This mutation was than confirmed in propositus’ platelet cDNA. The Val35Leu substitution is close to the thrombin cleavage site, the G226T substitution is in the catalytic core domain. This case demonstrates that in some cases of Factor XIII deficiency there is residual Factor XIIIa activity in the mutant molecule that can prevent serious bleeding. However, patients may develop autoantibodies that further interfere with Factor XIII function and may suffer serious bleeding complications. Additional cases of Factor XIII deficiency may exist in patients that have mild bleeding problems.