Inherited factor V deficiency associated with a novel heterozygous missense mutation (p.G493R) in a patient with excessive surgical bleeding.

摘要

Blood coagulation factor V (FV) is a single-chain glycopro-tein (Mr 330 kDa) synthesised in the liver and megakaryo-cytes. Its plasma concentration is 20 nM (7 (mug/mL) and approximately 20% of total FV is found in platelet a-granules (1). FV has a mosaic-like structure, with a domain organisation (A1-A2-B-A3-C1-C2) that shows high similarity to factor VIII (FVIII) (2). FV, an essential cofactor of activated factor X, is activated by thrombin. Thrombin removes the B-domain and the remaining heavy chain and light chain are associated via a calcium ion (3,4). Activated FV (FVa) enhances the rate of prothrombin activation by several orders of magnitude (3). The gene for FV (F5) has been localised to chromosome 1q21-25; it spans approximately 80 kilobases and consists of 25 exons and 24 introns (5).