Objective: To investigate potential mutations and clinical features of 9 unrelated patients with inherited coagulation factor VII (FVII) deficiency.
Methods: Clinical diagnosis was validated by assaying of coagulation parameters including prothrombin time, activated partial thromboplastin time, FVII activity and specific antigens. All exons, exon-intron boundaries, and 5' and 3' untranslated regions of F7 genes were amplified with PCR. Potential mutations were detected by direct sequencing of purified PCR products. Suspected mutations were confirmed by sequencing of the opposite strand.
Results: All probands have featured prolonged prothrombin time, with FVII activity ranging between 2.0% to 6.0%. The titers of FVII antigen were significantly reduced in 7 probands. Eight mutations, including 6 missense mutations, 1 deletion and 1 insertion, were identified, among which 3 (Gln100Leu, Ser269Pro and g.11520_11521insT) were not described previously. Six mutations have located in the protease domain. All mutations were inherited, and consanguineous marriages were reported in 5 families. Mutations g.27_28delCT, Cys329Gly, Arg304Trp and His348Gln have been identified in unrelated families. There was a lack of correlation between the mutations and their clinical features. Two individuals with homozygous His348Gln mutations and 1 individual with homozygous Arg304Trp mutation were only mildly affected or asymptomatic. Two patients, who have respectively carried homozygous and heterozygous deletions of g.27_28delCT, were moderately affected and asymptomatic. In 4 patients carrying double heterozygous mutations, 1 (Ser269Pro and Cys329Gly) was asymptomatic, 2 (Arg304Trp and Cys329Gly, Arg277Cys and g.11520_11521insT, respectively) had a mild bleeding tendency, whilst 1 (Gln100Leu and His348Gln) has a moderate bleeding diathesis.
Conclusion: There seem to be hotspots of F7 gene mutations in ethnic Han Chinese populations. And there is a lack of correlation between particular types of mutations and clinical phenotypes.