Dysfibrinogenemia

The dysfibrinogenemias consist of three types of fibrinogen disorders in which a critical blood clotting factor, fibrinogen, circulates at normal levels but is dysfunctional. Congenital dysfibrinogenemia is an inherited disorder in which one of the parental genes produces an abnormal fibrinogen. This fibrinogen interferes with normal blood clotting and/or lysis of blood clots. The condition therefore may cause pathological bleeding and/or thrombosis. Acquired dysfibrinogenemia is a non-hereditary disorder in which fibrinogen is dysfunctional due to the presence of liver disease, autoimmune disease, a plasma cell dyscrasias, or certain cancers. It is associated primarily with pathological bleeding. Hereditary fibrinogen Aα-Chain amyloidosis is a sub-category of congenital dysfibrinogenemia in which the dysfunctional fibrinogen does not cause bleeding or thrombosis but rather gradually accumulates in, and disrupts the function of, the kidney. Congenital dysfibrinogenemia is the commonest of these three disorders. Some 100 different genetic mutations occurring in more than 400 families have been found to cause it. All of these mutations as well as those causing hereditary fibrinogen Aα-Chain amyloidosis exhibit partial penetrance, i.e. only some family members with one of these mutant genes develop dysfibrinogenemia-related symptoms. While both of these congenital disorders as well as acquired dysfibrinogenemia are considered very rare, it is estimated that ~0.8% of individuals with venous thrombosis have either a congenital or acquired dysfibrinogenemia. Hence, the dysfibrinogenemia disorders may be highly under-diagnosed conditions due to isolated thrombotic events that are not appreciated as reflecting an underlying fibrinogen disorder. Congenital dysfibrinogenemia is distinguished from a similar inherited disorder, congenital hypodysfibrinogenemia. Both disorders involve the circulation of dysfunctional fibrinogen but in congenital hypodysfibrinogenemia plasma fibrinogen levels are low while in congenital dysfibrinogenemia they are normal.