[Identification of two novel mutation in two Chinese hereditary coagulation factor XIII deficiency families].

To explore gene defect of hereditary coagulation factor XIII deficiency.PCR and gene sequencing or ARMS-PCR were used to detect the FXIIIA gene of peripheral white blood cell (PBC) from two Chinese hereditary coagulation factor XIII deficiency family members and 60 normal subjects respectively. The level of FXIIIA gene mRNA was tested by RT-PCR.(1) Nucleotide sequence analysis of the two probands' and their family members' DNA revealed that all of the three patients had homozygous missense mutation in FXIII A subunit gene. Proband 1 had a C to G transition at nucleotide (nt) 1 241 in exon 10 and proband 2 and his sister a C to T transition at nt 232 in exon 3 of FXIII A gene, which resulted in the substitution of Ser413 with Trp and Arg 77 with Cys, respectively. Family study showed that the two mutations were inherited from the parents who were correspondingly heterozygotes at nt 1 241 or nt 232. (2) The two mutations were not found in the normal subjects. (3) The FXIIIA gene mRNA level in the two probands was a little decreasing.It is the two novel mutations that results in FXIIIA deficiency. The two mutations of FXIIIA gene may affect its function or alter protein folding. The defective FXIII which is unstable and degraded rapidly in cytoplasm may be the main cause of FXIII deficiency.