Role of genetic prothrombotic risk factors in childhood caval vein thrombosis

Childhood caval vein thrombosis has a high incidence especially in the firs t year of life. Besides deficiencies of protein C, protein S, antithrombin and plasminogen, the factor (F) V G1691A mutation, the prothrombin (PT) G20 210A variant, the methylenetetrahydro-folate reductase (MTHFR) TT677 genoty pe, or increased lipoprotein (Lp) (a) > 30 mg/dl have emerged as important prothrombotic risk factors in childhood vascular accidents. 27 consecutive childhood patients with inferior caval vein thrombosis and 100 healthy age- matched controls were investigated for the presence of these prothrombotic risk factors with respect to the first thrombotic onset. In 19 out of 27, p atients thrombosis occurred during infancy; the remaining vascular accident s were diagnosed during puberty. In 13 out of the 19 infants, vascular occl usion occurred spontaneously, five times associated with renal venous throm bosis. 68.4% of patients in the first year of life (n = 13) showed at least one prothrombotic risk factor. The FV mutation (heterozygous n = 4, homozy gous n = 1), Lp (a) > 30 mg/dl and kringle 4 repeats < 28 (n = 4), MTHFR TT 677 with mild hyperhomocysteinaemia (> 95th age-dependent percentile, i.e. 8.5 mu mol/l: n = 3) and antithrombin deficiency type II (n = 1) were diagn osed with an overall odds ratio/95% confidence interval of 9.2/3.1-27.4. In the adolescent group, genetic risk factors were found in 50% of patients i nvestigated (FV mutation (n = 1), PT variant (n = 3); odds ratio/95% confid ence interval: 4.2/0.97-18.6). Conclusion Data presented here suggest that genetic prothrombotic risk fact ors:play an important role in childhood caval vein thrombosis. Remarkably, during puberty and adolescence the predominant defect diagnosed was the PT G20210A variant, whereas the FV G1691A mutation had a higher incidence duri ng infancy.