A RARE COAGULATION DISORDER - FACTOR X DEFICIENCY

Abstract

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