Type I coagulation factor V deficiency caused by compound heterozygous mutation of F5 gene

A 16-year-old Chinese female with prolonged bleeding after surgery has been studied. Routine clotting tests revealed a prolonged activated partial thromboplastin time (APTT; 126.6 s) and prothrombin time (PT; 42.8 s). The coagulation factors activities were normal except for factor V, which was only 0.3% of normal. DNA analysis of the FV gene revealed five nucleotide substitutions in exons, including two silent mutations (G327A and A5112G), one polymorphism (G1628A), a G1348T missense mutation and 4887similar to8delG. These abnormalities were associated with her FV deficiency, perhaps by causing a Gly392Cys substitution in FV amino acid sequence or by introducing a premature stop codon at amino acid position 1390. This is the third case in which FV deficiency is caused by compound heterozygous mutation of F5 gene, and is the first report from a Chinese family.