Congenital factor II deficiency

Congenital factor II (prothrombin) deficiency is an extremely rare inherited bleeding disorder caused by mutations in the F2 gene located on chromosome 11. Factor II (prothrombin) is a key protein in the coagulation cascade that is converted to thrombin, which in turn converts fibrinogen to fibrin to form blood clots. This condition can present in two forms: type I (hypoprothrombinemia), characterized by reduced levels of prothrombin protein and activity, and type II (dysprothrombinemia), characterized by normal or near-normal protein levels but reduced functional activity. Complete absence of prothrombin is thought to be incompatible with life. The disease primarily affects the hematologic system, leading to a variable bleeding tendency that can range from mild to severe. Key clinical features include easy bruising, prolonged bleeding after surgery or trauma, epistaxis (nosebleeds), menorrhagia (heavy menstrual bleeding) in women, gum bleeding, and in severe cases, hemarthrosis (joint bleeding), gastrointestinal bleeding, intracranial hemorrhage, and umbilical cord bleeding in neonates. Symptoms often present in childhood, though milder cases may not be recognized until later in life when a hemostatic challenge occurs. There is no specific factor II concentrate widely available for treatment. Management of bleeding episodes and surgical prophylaxis typically involves the use of fresh frozen plasma (FFP) or prothrombin complex concentrates (PCCs), which contain factor II along with other vitamin K-dependent clotting factors. Antifibrinolytic agents such as tranexamic acid may be used as adjunctive therapy, particularly for mucosal bleeding. Patients should avoid antiplatelet medications and be counseled regarding bleeding precautions. Genetic counseling is recommended for affected families.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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