Objective To explore the molecular pathogenic mechanism of a new variant of F5 gene with a complex heterozygous hereditary coagulation factor V(FV)deficiency in a pedigree.Methods To detect the related coagulation indexes of the proband and his family members(10 persons in 3 generations).Thrombin generation was detected by CAT method.Direct sequencing was used to analyze all exons and their flanking sequences of the proband F5 gene.The conservation of amino acid variation sites and the impact of variation on protein function were analyzed by bioinformatics software.Variation sites were rated according to the American College of Medical Genetics and Genomics(ACMG)variation rating guidelines.Results The prothrombin time(PT)of the proband was 25.2 s and the activated partial thrombin time(APTT)was 84.4 s,both of which were significantly prolonged.Plasma FV activity(FV:C)and FV antigen(FV:Ag)were extremely reduced at 6％and 8％,respectively.Decreased thrombin production and prolonged peak time in the proband.Gene sequencing found that the proband had a paternal source c.4594C＞T(p.Gln1532*)heterozygous nonsense mutation in exon 13 and a maternal c.6665A＞G(p.Asp2222Gly)heterozygous missense mutation in exon 25.Conversion analysis showed that Gln1532 was highly conserved.Three online bioinformatics software Mutation Taster,SIFT,and PolyPhen-2 showed that the two mutations were deleterious mutations.Protein model analysis showed that the p.Gln1532*mutation resulted in the loss of the entire light chain of FV.According to the ACMG variant rating guidelines,the new variation c.4594.C＞T was rated as a probable patho-genic variant(PM2+PM4+PP1+PP3+PP4).Conclusion The c.4594C＞T heterozygous nonsense mutation in exon 13 and the c.6665A＞G heterozygous missense mutation in exon 25 of the F5 gene are considered to be thepathogenesis of this FV defi-ciency family,of which the c.4594C＞T nonsense mutation of F5 gene is first reported internationally.
关键词
凝血因子V缺陷症/F5基因/新变异位点/B结构域
Key words
coagulation factor V deficiency/F5 gene/new mutation site/B domain
维普
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