Background: Factor V congenital deficiency is a rare hereditary disease, it exposes patients to hemorrhagic risk, with high morbi-mortality.

Aims: To analyze the clinical phenotype and molecular pathogenesis of 9 patients with hereditary  FV deficiency.

Methods: Nine patients with hereditary FV deficiency who were admitted to the Institute of Hematology & Blood Diseases Hospital from April 1999 to September 2019 were analyzed: activated partial thromboplastin time (APTT), prothrombin time (PT) and FV procoagulant activity (FV:C) were measured for phenotypic diagnosis; high-throughput sequencing was used for F5 gene mutations screening; Sanger sequencing was used to confirm candidate variants and parental carrying status; Swiss-model was used for three-dimensional structure analysis; ClustalX-2.1 software was used for homologous analysis.

Results: The FV:C of 9 patients ranged from 0.1 to 10.6. Among them, 8 patients had a history of hemorrhage, with kin/mucosal bleeding was the most common symptom (3 cases, 37.5%), while 1 case had no bleeding symptom. There were 5 homozygotes and 4 compound heterozygotes. A total of 12 pathogenic or likely pathogenic mutations were detected, of which c.6100C>A/p.Pro2034Thr, c.6575T>C/p.Phe2192Ser, c.1600_1601delinsTG/p. Gln534*, c.4713C>A/p.Tyr1571* and c.952+5G>C were reported for the first time.

Conclusions: The newly discovered gene mutations enriched the F5 gene mutation spectrum which associated with hereditary FV deficiency. High-throughput sequencing could be an effectively method for the detection of F5 gene mutations.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/clinical-and-genetic-analysis-of-nine-cases-of-hereditary-factor-v-deficiency/