FACTOR X (Stuart-Prower Factor) DEFICIENCY
Factor X (FX), or Stuart-Prower factor, deficiency was first identified in the 1950s in the US and England in two patients: Rufus Stuart and Audrey Prower. The incidence of FX deficiency is estimated at 1 in 500,000 to 1 in a million. Inheritance is autosomal recessive, meaning females and males can equally be affected. The factor X protein plays an important role in activating the enzymes that help to form a clot. It needs vitamin K for synthesis, which is produced by the liver.
People with mild FX deficiency experience easy bruising, nose or mouth bleeds, and bleeding after trauma or surgery. Symptoms for patients with severe FX deficiency include excessive umbilical cord bleeding, joint bleeds, intramuscular bleeds, and a high risk of intracranial hemorrhage in the first weeks of life.
Women with FX deficiency may additionally exhibit menorrhagia, or heavy menstrual bleeding. Pregnant women with FX may experience first trimester miscarriage or post-partum hemorrhage and should receive consultation by a hematologist and obstetrician prior to delivery.
Diagnosis is made through family history, prothrombin time (PT) test, partial thromboplastin time (PTT) or activated partial thromboplastin time (APTT) test. Diagnosis can be confirmed by a FX assay.
In October 2015, the U.S. FDA approved Coagadex®, a coagulation Factor X (Human) product, manufactured by Bio Products Laboratory (BPL). Coagadex®, a plasma derived concentrate, is indicated for adults and children with hereditary Factor X deficiency for routine prophylaxis to reduce the frequency of bleeding episodes, on-demand treatment and control of bleeding episodes, and for the perioperative management of bleeding in patients with mild and moderate hereditary Factor X deficiency.
Prior to this product becoming available, fresh-frozen plasma (FPP) or plasma-derived prothrombin complex concentrates (PCCs) were the only options for the treatment of bleeds. However, the amount of FX varies between PCCs (and from lot to lot). Treatment with PCCs should be used cautiously because at higher volumes they can produce blood clots.
Antifibrinolytic agents, such as aminocaproic acid or tranexamic acid, or topical therapies, such as nosebleed powders or fibrin glue, may relieve bleeding symptoms in patients with mild symptoms.