Influence of the-675 4G/5G dimorphism of the plasminogen activator inhibitor 1 promoter on thrombotic risk in patients with factor V Leiden

Elevated plasminogen activator inhibitor 1 (PAI-1) levels are associated wi th venous thromboembolism. although their significance is unclear. PAI-1 le vels are influenced by a PAI-1 promoter dimorphism (4G/5G), the 4G allele b eing associated with increased PAI-1 activity We investigated whether the 4 G allele influenced thrombotic risk by studying 99 symptomatic factor V (FV ) Leiden heterozygotes and 99 healthy subjects. The 4G allele was more prev alent among cases than among healthy subjects (chi(2) = 8.00, P = 0.005) an d the odds ratio (OR) for thrombosis associated with either heterozygosity or homozygosity for the 4G allele was 3.43 (P = 0.011). We conclude that ca rriership of the 4G allele was more prevalent in patients who already carri ed factor V Leiden than in control subjects without factor V Leiden.