Platelet polymorphisms: frequency distribution and association with coronary artery disease in an Indian population

Platelets play a critical role in normal blood hemostasis and thrombus formation in myocardial infarction (MI). Several polymorphisms of genes involved in platelet activation and fibrinolysis have been reported to be associated with MI. The aim of the present study was to determine the frequency distribution and association of polymorphisms in these genes with coronary artery disease (CAD) among Indians. A case-control genetic association study was performed for polymorphisms in platelet glycoprotein receptors (GPIIb/IIIa [HPA1a/1b], GPIb-IX-V [VNTR], and GPIa/IIa [C807T]), fibrinogen β-chain (BclI), α-chain (Aα312), tissue plasminogen activator (tPA) [I/D] and plasminogen activator inhibitor-I (PAI-1) [4G/5G] in 473 healthy controls and 446 patients with stable and unstable angina. Genotyping was either by PCR-based restriction endonuclease digestion or allele-specific primers. The I allele frequency of the tPA I/D polymorphism was significantly higher in our patients (χ(2)=7.33, P<0.01) and no other polymorphisms varied significantly between patients and controls. Also, none of the polymorphisms seemed to affect the severity of the disease, the only exception being the mutant alleles of β chain of fibrinogen gene, which were significantly elevated in single vessel disease. This is the first study to evaluate the role of gene polymorphisms in both the thrombotic and fibrinolytic pathway in the Indian population and suggests that tPA I/D polymorphism confers CAD risk in our population.