Abstract • 137

Aim: To evaluate the prevalence of FV Leiden and mutant FII in several groups of children with or without thrombosis. Patients: A total of 145 individuals(neonates: 36, thrombosed children: 30, children with CNS thrombosis: 32, family members of thrombosed children: 15, children suspective of thrombosis: 17, haemophiliacs: 15) were tested for FV Leiden. Besides, 115/145 children were tested for mutant FII (family members and haemophiliacs not tested). The age of children ranged from 4-18 years. Methods: DNA isolation from anticoagulated whole blood, in vitro amplification (PCR) of FV and FII gene sequences, detection of the mutation by allele-specific hybridization (Vienna Lab Kit). Results: 12/145 studied subjects were found to have the FV Leiden allele (8.3%), eleven heterozygotes and one homozygote (neonates 2/36, thrombosed children: 3/30, CNS thrombosis: 2/32, suspective thrombosis: 2/17, family members 3/15). The prevalence of FV Leiden in thrombosed and non thrombosed children was 8.3% (5/62) and 5.8% (4/68), respectively. Besides, 2/115 studied individuals (1.7%) were found to have the prothrombin mutation. One patient suffering from extensive thrombosis at multiple sites was homozygous for the defect. The prevalence of mutant FII was 3.2% (2/62) and 0/53 in thrombosed and non thrombosed patients, respectively. Thromboembolic events ravely occur during childhood, however FV Leiden or mutant FII seem to be a possible risk factor of thrombosis.