A RARE COAGULATION DISORDER - FACTOR X DEFICIENCY

29 year old female presenting with hematuria and recurrent episodes of bleeding manifestations since childhood was evaluated. She had no other specific complaints. She had an affected younger sibling also. Her aPTT was prolonged with normal platelet counts, Bleeding time, Prothrombin time and Thrombin time. Evaluation using mixing studies revealed the presence of Factor X deficiency. Her parents were also asymptomatic carriers of the disease. Factor X is the zymogen of factor Xa, a Vitamin K dependent serine protease. It is the first enzyme in the common pathway of thrombus formation. Factor X is otherwise called the Stuart-Prower factor. It is one of the world's most rare factor deficiencies with an estimated frequency of 1 in one million persons. Phenotypically, factor X deficiency is classified as either type I, distinguished by reduced factor X activity and reduced factor X antigen, or type II, distinguished by reduced factor X activity but normal factor X antigen. CRM -negative is type I and CRM-reduced to CRM-positive is type II. Factor X deficiency is associated with normal thrombin times but prolonged PT and aPTT, particularly among the CRMnegative variants. Unfortunately, factor X deficiency variants have been described with isolated prolonged PT or aPTT values. Treatment is infusion of fresh frozen plasma or Purified Prothrombin Complexes