What is the most common cause of inherited thrombophilia?

What is the most common cause of inherited thrombophilia?

• A. Antiphospholipid syndrome
• B. Prothrombin G20210A mutation
• C. Factor V Leiden
• D. Hyperhomocysteinemia

Answer: (C)

Factor V Leiden is the most common inherited thrombophilia. It’s a genetic variant of coagulation factor V (the R506Q mutation) that makes Factor V resistant to inactivation by activated protein C. Normally, activated protein C dampens clot formation by inactivating Factor Va, but when Factor V Leiden persists longer, more thrombin is produced and the tendency to form clots increases. This inherited defect is especially prevalent in people of European ancestry, where a notable percentage carry the mutation. Other options include an acquired autoimmune condition (antiphospholipid syndrome), another inherited mutation that’s less common in many populations (prothrombin G20210A), or a metabolic risk factor (hyperhomocysteinemia); while these can contribute to thrombosis, they’re not as consistently the most common inherited cause as Factor V Leiden.

Factor V Leiden is the most common inherited thrombophilia. It’s a genetic variant of coagulation factor V (the R506Q mutation) that makes Factor V resistant to inactivation by activated protein C. Normally, activated protein C dampens clot formation by inactivating Factor Va, but when Factor V Leiden persists longer, more thrombin is produced and the tendency to form clots increases. This inherited defect is especially prevalent in people of European ancestry, where a notable percentage carry the mutation. Other options include an acquired autoimmune condition (antiphospholipid syndrome), another inherited mutation that’s less common in many populations (prothrombin G20210A), or a metabolic risk factor (hyperhomocysteinemia); while these can contribute to thrombosis, they’re not as consistently the most common inherited cause as Factor V Leiden.