New polymorphisms in the interleukin-10 gene--relationships to myocardial infarction

Interleukin-10 (IL-10) is a cytokine with anti-inflammatory and B-cell-stimulating activity. IL-10 is expressed in human atherosclerotic plaques and recent studies have shown the involvement of IL-10 in the atherosclerotic process. Therefore, we hypothesized that polymorphisms in the IL-10 gene might be associated with a predisposition to coronary heart disease.

To identify new polymorphisms in the human IL-10 gene, the entire coding sequence and the 3' flanking sequence of the gene were screened by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCR) followed by sequencing. The polymorphisms identified, and three others which have been previously described in the promoter region of the IL-10 gene (G-1082A, C-819T, C-592A), were then investigated in the ECTIM Study, a large population-based case-control study of myocardial infarction.

Four new polymorphisms were identified: one in exon 1 (G+78/ex1A), which predicts a Glycine to Arginine change at position 15 in the putative signal peptide of the protein, two in the intron 3 (C+19/in3T, T+953/in3C) and one in the 3' flanking region (C+117T). All the IL-10 polymorphisms were in complete or nearly complete pairwise linkage disequilibrium. No case-control difference was found in genotype or allele frequencies for any of the polymorphisms.

Our results suggest that IL-10 polymorphisms are not associated with an increased risk of myocardial infarction.