Glycoprotein IIIa Polymorphism and Risk of Myocardial Infarction

Objectives: To prospectively investigate whether the PlA2 variant of the platelet adhesion molecule glycoprotein IIIa influences the risk of myocardial infarction.

Background: The platelet glycoprotein IIb/IIIa receptor plays an important role in platelet aggregation. The IIIa polypeptide is polymorphic due to a single base change at position 1565 resulting in either proline PlA1 or leucine PlA2 at position 33 in the protein. It has recently been reported that the PlA2 variant may be strongly associated with the risk of acute coronary syndromes, particularly in younger subjects.

Methods: PlA genotypes of 242 prospectively collected cases of first myocardial infarction admitted to our Coronary Care Unit were compared with those of 209 community-based control subjects.

Results: We found no difference in either PlA genotype (P = 0.65) or allele (P = 0.64) frequencies between cases and controls. The PlA2 allele frequency was 18.2 and 19.4% in cases and controls, respectively. The age- and sex-stratified odds ratio for risk of myocardial infarction associated with the PlA2 allele was 0.89 (95% CI 0.58-1.37, P = 0.65) and remained non-significant when the analysis was confined to subjects under the age of 60 (odds ratio 0.77, 95% CI 0.38-1.56, P = 0.44). There was no interaction between PlA2 and other coronary risk factors. For cases, the age at myocardial infarction was not different between those carrying the PlA2 allele and those not (66.3 +/- 10.8 vs. 65.6 +/- 11.7 years, P = 0.63).

Conclusions: We conclude that, in our subjects, the PlA2 variant of platelet glycoprotein IIIa is not an important risk factor for myocardial infarction.