Objective: To explore molecular etiology and clinical characteristics of two pedigrees affected with hereditary factor VII(FVII) deficiency.
Methods: The nine exons and flanking sequences of the F7 gene of the probands were amplified by PCR. The amplicons were analyzed by direct sequencing. Suspected mutations were subjected to SWISS-MODEL modeling and analysis of protein structure change by Pymol software and conservation of amino acids across various species.
Results: For proband of pedigree 1, the prothrombin time (PT), FVII activity (FVII:C) and FVII antigen (FVII:Ag) were 36.3 s, 3%, 53.56%, respectively. Sequencing revealed a compound heterozygous variants of c.80_81delCT and c.1371G>T(p.Arg439Ser). His son carried a heterozygous c.1371G>T (p.Arg439Ser) variant. For proband of pedigree 2, the PT, FVII:C and FVII:Ag were 22.3 s, 4%, 1.58%, respectively. Sequencing has revealed a compound heterozygous c.278G>T(p.Arg75Met) missense variant in exon 3 and c.1278T>G (p.His408Gln) in exon 9 of the F7 gene. His mother and son both carried a heterozygous c.278G>T(p.Arg75Met) variant. Three-dimensional simulation and homology analysis revealed that the p.Arg439Ser and p.Arg75Met can respectively alter part of hydrogen bonds and two highly conserved amino acids.
Conclusion: Two novel heterozygous missense variants of the F7 gene [c.1371G>T(p.Arg439Ser) and c.278G>T(p.Arg75Met)] probably account for the decrease of factor VII in the two pedigrees.