Type I factor XIII deficiency is caused by a genetic defect of its b subunit: Insertion of triplet AAC in exon 11 leads to premature termination in the second Sushi domain - Izumi, T; Hashiguchi, T; Castaman, G; Tosetto, A; Rodeghiero, F; Girolami, A; Ichinose, A (Blood, 1996)