FV deficiency, FV Leiden, and F5-Atlanta are rare, recessive coagulation disorders caused by variants in the F5 gene. FV deficiency impedes an individual’s ability to clot, resulting in excess bleeding, whereas FV Leiden causes thrombophilia.
CLASSIFICATION AND DISTRIBUTION OF VARIANTS
- FV variants are classified as having a Type I or Type II phenotype. Type I variants are those resulting in decreased levels of FV antigen and FV activity, whereas Type II variants result in decreased FV activity but normal FV antigen.
- Most FV variants stem from point mutations, yet small insertions and deletions have also been detected throughout the F5 gene. All such variants result in the production of non-functional FV protein or truncated FV which undergoes cellular degradation.
- Whilst FV variants are spread across the entirety of the F5 gene, many are clustered in the serine protease (SP) domain, the catalytically active region of FV.
