Congenital
coagulation factor V deficiency (FVD) is a rare, autosomal recessive
bleeding disorder. We characterized the clinical presentations, laboratory features, and genetic alterations of Taiwanese patients with FVD. From 1983 to 2010, five women, one man, and one boy diagnosed with FVD were enrolled in this study. The
factor V coagulant activity was determined using a one-stage prothrombin time-based test. The
factor V antigen level was measured in an ELISA. Sanger sequencing was performed for genetic analyses of F5 , the gene responsible for the disease. One novel and de novo F5 genetic variant, p.Tyr1813 ∗ , was identified. Based on the presence of a
premature termination codon with a resultant truncated
factor V-
protein lacking an intact light chain fragment, the variant is pathogenic. In addition, we identified seven variants previously found to cause FVD. Among them, p.Gly420Cys and p.Asp96His were repeatedly detected in five and four patients, respectively. Both variants are found to be specific to the East Asian populations. Various FVD-associated
bleeding manifestations were observed, predominantly mucocutaneous
bleeding and
hypermenorrhea. All patients exhibited very low
factor V coagulant activity (<1-2.5 IU/dl, reference range: 60-133 IU/dl). The
factor V antigen level was less than 2% in six patients (reference range: 75-157%). The novel F5 genetic variant p.Tyr1813 ∗ and two distinct, East Asians-specific, recurrent variants p.Gly420Cys and p.Asp96His were identified among seven index patients with FVD in Taiwan. Our clinical and laboratory findings support the reported features of FVD.