Endothelial protein C receptor polymorphisms and risk of myocardial infarction.

BACKGROUND Haplotypes A1 and A3 in the endothelial protein C receptor gene are tagged by the 4678G/C and 4600A/G polymorphisms, respectively, and have been reported to influence the risk of venous thromboembolism. We assessed whether these haplotypes modify the risk of premature myocardial infarction. DESIGN AND METHODS We genotyped these polymorphisms in 689 patients with premature myocardial infarction and 697 control subjects. Activated protein C and soluble endothelial protein C receptor levels were also measured. RESULTS After adjustment for other cardiovascular risk factors, A1 and A3 haplotypes protected against premature myocardial infarction (odds ratio 0.7, 95% CI 0.4-0.8, p=0.044 and 0.5, 0.3-0.6, p<0.001, respectively). Moreover, the protective role of these haplotypes seemed to be additive, as carriers of both the A1 and A3 haplotypes had adjusted odds ratios of 0.3 (0.2-0.5, p<0.001) and 0.4 (0.2-0.8, p=0.006) compared to those carrying only the A1 or A3 haplotype, respectively. The presence of the A1 haplotype was associated with increased levels of activated protein C whereas individuals carrying the A3 haplotype showed the highest soluble endothelial protein C receptor levels. CONCLUSIONS These results show that A1 haplotype carriers have a reduced risk of premature myocardial infarction via the association of this haplotype with increased activated protein C plasma levels. The study also shows that carriers of the A3 haplotype have a reduced risk of myocardial infarction, only in part due to increased soluble endothelial protein C levels.