[Thrombophilic disorders in children and adolescents with portal vein thrombosis].
To determine the frequency of protein C, protein S and antithrombin deficiency, and factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T mutations in children and adolescents with portal vein thrombosis, as well as assessing the hereditary character of this disorders. A two-year study was carried out to determine the frequency of thrombophilic disorders in children and adolescents with portal vein thrombosis (n = 14), their parents (n = 24), and two control groups, one age-matched children and adolescents free of liver disease (n = 28) and another group with cirrhosis (n = 24). The portal vein thrombosis patients were investigated by clinical and laboratory means, esophagogastroduodenal endoscopy and liver biopsies. The presence of portal vein thrombosis was assessed by Doppler ultrasonography and/or angiographic analysis. The frequency of protein C, protein S and antithrombin deficiency was 6/14 (42.9%) (p < 0.05 versus controls), 3/14 (21.4%) (p > 0.05) and 1/14 (7.1%) (p > 0.05) of children and adolescents with portal vein thrombosis, respectively. The frequency of protein C, protein S and antithrombin deficiency in cirrhotic patients was 14/24 (58.3%), 7/24 (29.2%) and 11/24 (45.8%), respectively (p < 0.05 versus controls free of liver disease). None of the portal vein thrombosis parents or controls presented protein C, protein S or antithrombin deficiency. One portal vein thrombosis patient and one control (p = 0.999) presented prothrombin G20210A mutation. The homozygous form of methylenetetrahydrofolate reductase C677T mutation was observed in 3/14 (21.4%) patients with portal vein thrombosis and in 5/28 (17.9%) (p = 0.356) controls. None of the patients or controls presented the factor V Leiden. Half of the children and adolescents with portal vein thrombosis presented deficiency of one or more coagulation inhibitor proteins, mainly protein C, but this deficiency does not seem to be an inherited condition. The hereditary prothrombotic disorders do not seem to play a vital role in thrombosis in patients with portal vein thrombosis of this study. In the cirrhotic patients, there was a higher frequency of protein deficiency when the disease was more intense.