Influence of the 4G/5G polymorphism of plasminogen activator inhibitor-1 gene in acute unprovoked deep vein thrombosis and residual vein thrombosis

Background Plasminogen activator inhibitor-1 (PAI-1) is an important inhibitor of plasminogen activator, but the role of the PAI-1 4G/5G polymorphism in deep vein thrombosis (DVT) has been contradictory. In this study, we investigated the distribution of the PAI-1 4G/5G genotype in Chinese patients with DVT compared with healthy controls and the association between the PAI-1 4G/5G genotype and the persistence of residual venous occlusion (RVO) after different treatments. Methods The PAI-1 4G/5G genotype was determined by fluorescence in situ hybridization in 108 patients with unprovoked DVT and 108 healthy controls. The patients with DVT were treated with catheter-based therapy or anticoagulation only. RVO was assessed by duplex sonography during the follow-up. Results Thirty-two patients (29.6%) were homozygous for 4G (4G/4G), 62 patients (57.4%) were heterozygous for 4G/5G, and 14 patients (13%) were homozygous for 5G (5G/5G). No significant difference in genotype frequency was found between patients with DVT and controls. A total of 86 patients completed follow-up of ultrasound examination with a mean follow-up of 13.4 ±7.2 months. The results of patients with RVO were significantly different between homozygous 4G carriers (76.9%), heterozygous 4G/5G (58.3%), and homozygous carriers of 5G (33.3%) (P <.05) at the end of follow-up. Catheter-based therapy showed a better result in patients who were noncarriers of 4G (P = .045). Conclusions The PAI-1 4G/5G genotype was not a relevant predictor for DVT in Chinese patients, but is a risk factor for persistent RVO after idiopathic DVT.