Factor V Leiden Mutation (Resistance to Activated Protein C)
- Most common inheritable cause of thrombophilia (3-8% caucasians; 1%
African American)
- Autosomal dominant
- Arg -> Glutamine at the #506 position of the Factor V protein (R506Q)
- now Protein C can’t bind and inhibit Factor V…therefore
Factor V has unopposed clotting
activity
- Heterozygotes -3x increase risk of thrombosis Homozygotes -30x
- Usually have other “2nd hit” to cause thrombosis in pediatric population
- Tests:
- APC (activated Protein C) Ratio: (<2.0 abnl)
- PCR for Factor V
Return to Hypercoaguable states
CHLA Board Review 2005