PS1100 CONGENITAL FACTOR V DEFICIENCY FROM COMPOUND HETEROZYGOUS MUTATIONS WITH A NOVEL MUTATION C.2426DEL (P.PRO809HISFS ∗ 2) IN THE F5 GENE

Background: Congenital factor V deficiency (FVD) is a rare bleeding disorder characterized by low or undetectable plasma FV levels leading to mild to severe bleeding symptoms. Currently, more than 100 mutations have been reported in F5 . The majority of F5 mutations are missense mutations (61.5%), and small deletion and splicing mutations account for 18.5% and 11.9%, respectively. Aims: We herein report a patient with FVD from compound heterozygous mutations including a novel deleterious mutation. Methods: The patient was a 52‐year‐old man with prolonged PT and aPTT corrected by mixing test on preoperative screening. His past medical or family history was not remarkable. Factor assays revealed a markedly reduced FV activity at 7%. Other factors were not decreased. DNA sequencing analysis to detect F5 gene mutations was performed after obtaining written informed consent. Results: Two different heterozygous mutations in F5 were detected: a missense variant (c.286G>C [p.Asp96His]) and a frameshift variant from small deletion (c.2426del [p.Pro809Hisfs ∗ 2]). The Asp96His was previously described missense mutation and Pro809Hisfs ∗ 2 was a novel deleterious mutation. Summary/Conclusion: We herein report an asymptomatic patient with FVD from compound heterozygous mutations of F5 including a novel frameshift mutation. As was the case in our patient, genotype‐phenotype correlations are poor in FVD, and molecular genetic test is necessary to confirm the diagnosis.