F5 and hemorrhagic disease: FV deficiency itself is a bleeding disorder, while FV Leiden is a risk factor for clotting, both of which are associated with genetic variants in theF5gene which codes for FV.1, 2The full-length humanF5gene has 25 exons (OMIM #612309; Gene ID #2153) spanning approximately 80 kb and is located on chromosome 1 (1q24).3The mRNA with 25 exons (Fig. 1) contains 6,672 bp, corresponding to a protein with 2,224 amino acids and a molecular mass of 330 kDa.