Leiden mutation of the coagulation factor V is the most frequent known congenital risk factor of thrombophilia. The authors examined a group of 440 subjects with thrombosis in the case- or family-history. The mutation was found in 146. In 94 thrombotic manifestations were recorded in the case-history, five women were examined because of repeated abortions. 52.74% carriers of FVL had venous thrombosis of the lower extremities and pelvis in their case-history, 19.18% had pulmonary embolism in the case-history. In 27.40% during the initial manifestations of thrombosis no other risk factor of thrombosis was detected. In 10.27% the first thrombosis developed after an injury or operation. In 22.22% women the thrombosis was manifested during pregnancy or the puerperal period. Due to the high incidence of this defect screening of the resistance to activated protein C should be an integral part of examination of thrombophil conditions.

Keywords: Adolescent; Adult; Aged; Child; Child, Preschool; Factor V /genetics/; Female; Humans; Infant; Male; Middle Aged; Mutation; Pregnancy; Pregnancy Complications, Cardiovascular; Thrombophilia /genetics/; Thrombosis /genetics/