Congenital factor XIII deficiency: report of a case and literature review.

We described a five-year-old boy with congenital deficiency of factor XIII. He had bled from the umbilical and circumcision sites during the first week of life. He had frequent ecchymoses and hematomas within 12-24 hours after trauma. His parents are first cousins. The screening hemostatic tests of this patient and his parents were within normal limits. Factor XIII, known as "fibrin-stabilizing factor", is a transpeptidase that produces strong covalent bonds between soluble fibrin monomers formed during coagulation. Presumptive diagnosis of factor XIII deficiency was made with a clot solubility screening test and confirmation was accomplished by demonstrating the absence of factor XIII by latex agglutination.