Inherited thrombophilias - relative risk stratification
Core concept
- Two mechanistic families
- Loss of anticoagulant - antithrombin, protein C, protein S deficiency (rare, high risk)
- Gain of procoagulant - factor V Leiden, prothrombin G20210A (common, low risk)
- Prevalence and risk run in opposite directions - the common ones barely matter, the rare ones matter a lot
- Factor V Leiden - Arg506Gln point mutation makes FVa resistant to cleavage by activated protein C
- Prolonged FVa activity -> inc thrombin generation
- Also removes FV's cofactor role for APC in inactivating FVIIIa
- Prothrombin G20210A - 3' untranslated region variant -> inc prothrombin mRNA stability -> ~25% higher prothrombin level
- Antithrombin inhibits thrombin, Xa, IXa, XIa - the heparin cofactor; protein C/S inactivate FVa and FVIIIa
3 more sections, plus exam facts
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