Clinical aspects and laboratory problems in hereditary thrombophilia

Hereditary thrombophilia is a multifactorial disease which is mono- or plur igenic and its clinical expression is associated with a heterogeneous expre ssion. Factor V (FV) Leiden and FII gene mutations are more frequent than a ntithrombin, and protein C and S deficiencies. All thrombophilias are not t he same. Heterozygous carriers of FV Leiden or FII gene mutation have a wea ker risk of venous thrombosis. The mean age at the first episode is older i n the former and higher rate of recurrences is observed in the latter. The cosegregation of mutations significantly increases the risk of thrombosis. Both mutations have a geographic and ethnic distribution in relation with a gene founder effect. Clinical expression consists of deep or superficial v enous thrombosis with or without pulmonary embolism, thromboses at unusual sites (e.g. cerebral, portal, mesenteric) or with an increased incidence of fetal loss and abortion. A precipitating cause is present in more than 50% of patients. The risk pf arterial thromboses seems to be restricted to som e protein S and FII gene mutations. Laboratory diagnosis strategy should be oriented by careful selection of patients and preanalytical variables shou ld be considered. It is highly probable that other unindentified gene mutat ions are, at least partly, other causes of the heterogeneous expression of hereditary thrombophilia. Copyright (C) 1999 S. Karger AG, Basel.