A Case Report on an Extremely Rare Disease: Factor XI Deficiency.

Factor XI deficiency is a rare condition with an estimated prevalence of about one in one million and is more commonly seen in Ashkenazi Jews (8-9%) due to consanguinity. It occurs because of mutations in the factor XI gene (F11) on chromosome 4(4q35). Patients with this disorder may remain asymptomatic until they undergo any surgical procedure or delivery. The most common sites of bleeding include the oral cavity, pharynx, and genitourinary tract, where there is high fibrinolytic activity. Our patient was asymptomatic his whole life. He never had spontaneous bleeding or bruising; however, he had severe bleeding requiring multiple transfusions of fresh frozen plasma during and after surgeries.