Thrombophilia, which may be congenital or acquired, is a clotting disorder associated with hypercoagulability that causes the appearance of deep venous thrombosis (DVT). Herein, we discuss only congenital thrombophilia, in other words anomalies in patients with a familial history of thrombosis. We do not describe situations involving acquired hypercoagulability (e.g. antiphospholipid syndrome, cancer, etc.).