Paediatric thrombo-embolism : the influence of non-genetic factors and the role of activated protein C resistance and protein C deficiency

In many children, the pathogenesis of thrombo-embolism remains unexplained. This study examines the role of non-genetic risk factors in 37 children with venous or arterial thrombosis. Included were 17 patients with portal vein thrombosis following umbilical vein catheterisation, 6 with portal vein thrombosis and an uneventful neonatal period, 4 with deep vein thrombosis, 4 with renal vein thrombosis after kidney transplantation, 1 haemodialysis patient with thromboses of arteriovenous shunts, and 5 with arterial thromboses at various sites. In 25 of these 37 patients (68%) exogenic risk factors and particularly vascular manipulations (24/37) were related to the thrombotic event. Resistance to activated protein C was identified in 5 patients and protein C deficiency in 2 (7/37; 19%). This prevalence was significantly higher than that of the control group (14/243; 5.8%; chi 2, P < 0.008). Our data show that non-genetic and particular iatrogenic risk factors can often be identified in children with thrombosis, but activated protein C resistance and protein C deficiency are significant genetic risk factors in this age group.