[The Clinical Phenotype and Molecular Pathogenic Mechanism of a Family with Hereditary Coagulation Factor V Deficiency].

Objective: To investigate the clinical phenotype and molecular pathogenic mechanism of a hereditary coagulation factor V deficiency (FⅤD) family.

Methods: A phase I assay was used to measure coagulation factors II, V, VII, VIII, IX, X, Ⅺ, Ⅻ (FⅡ∶C, FⅤ∶C, FⅦ∶C, FⅧ∶C, FⅨ∶C, FⅩ∶C, FⅪ∶C, FⅫ∶C), activated partial thromboplastin time (APTT) and prothrombin time (PT) to determine the clinical phenotype and molecular pathogenesis of F VD. Prothrombin time (PT) were used for phenotypic identification; high-throughput exome sequencing was applied to screen the whole gene variants, and Sanger sequencing was used to verify the suspected variants in gene; MutationTaster, PolyPhen-2 bioinformatics software was used to predict the pathogenicity of the variants, ClustalX software was used to analyze the amino acid conservatism, and PyMol software was used to simulate the model of the mutant protein.

Results: The pre-documented patient had significantly prolonged PT and APTT, FⅤ∶C was only 5.45%, and there was no significant abnormality in TT, FIB and the rest of the coagulation factors. The mother, father and sister of the proband had prolonged PT and APTT, and FⅤ∶C was reduced to different degrees. Genetic testing revealed the presence of a c.286G>C (p.Asp96His) pure missense variant in exon 3 of in the prior witness, and a c.286G>C (p.Asp96His) heterozygous missense variant in father, mother, and sister of the proband. Bioinformatics analysis suggested that p.Asp96His was a pathogenic variant, and the associated amino acid site was highly conserved among 10 species. Protein simulation showed that the mutation of Asp96 to His96 could lead to the disappearance of the original hydrogen bond and the change of the distance, destroying the original hydrogen bond interaction force and affecting the stability of the protein structure.

Conclusion: The exon 3 c.286G>C (p.Asp96His) missense variant may have contributed to the reduction of FⅤ∶C in the preexisting individual and family members, as well as being the genetic etiology of coagulation factor V deficiency.