Objective: To analyze the gene mutation in two pedigrees of inherited coagulation factor VII (FVII) deficiency, and investigate the relationship between the genotype and phenotype.
Method: The coagulation function and coagulation factors activity of probands were detected for phenotype diagnosis, all exons and junctions of FVII gene from the family members' genomic DNA were amplified using polymerase chain reaction (PCR), and detected the gene mutation by direct sequencing. Mutations were confirmed by reverse sequencing.
Result: The prothrombin time (PT) of proband 1 was 265.2 s, FVII:C was 22% and the PT of proband 2 was > 120 s, FVII:C was 1%. Homozygous 17844G→A mutation in No. 8 exon of FVII gene was identified in the proband 1 resulting in Gly343Ser, and heterozygosity for the same mutations were confirmed in his parents and a sister. The proband 2 was compound heterozygous, one mutation was the same as the proband 1 but was a heterozygosity that can also found in his mother and brother; the other heterozygosity mutation was located on No. 8 exon 18055G→A that resulted in Gln413Arg which was inherited from his father.
Conclusion: No. 8 exon of FVII gene encodes catalytic domain. Mutation found in those domain could change the FVII catalytic domain spatial structure, affected FVII function and stability, and the sufferer of homozygote and compound heterozygous may have clinical bleeding tendency. Almost no clinical findings in simple heterozygotes, however, a few of heterozygotes could have a tendency of bleeding because of genetic polymorphism which would reduce the FVII:C.