Aim
Recent studies highlight the importance of the interleukin (IL)‐17A cytokine in systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). There are also reports of associations between some single nucleotide polymorphisms (SNPs) in IL‐17A and RA but not SLE. Notably, these findings have not been replicated in all studied populations. The aim of this study was to investigate whether the IL‐17A ‐737 T/C (rs8193036), ‐444A/G (rs3819024), ‐197G/A (rs2275913), and ‐121G/A (rs8193037) SNPs conferred susceptibility to SLE (or lupus nephritis) or to RA in a Mexican population.
Methods
The study included 1367 Mexican subjects, 501 with RA, 367 with SLE, and 499 healthy controls. IL‐17A was genotyped using a TaqMan 5ʹ allelic discrimination assay.
Results
Our results showed that the IL‐17A ‐737 T/C, ‐444A/G, ‐197G/A, and ‐121G/A SNPs had similar genotype and allele frequencies in patients with SLE (or lupus nephritis) or RA and in controls. However, an IL‐17A haplotype (TAGA) showed an association with SLE susceptibility (odds ratio 2.43, P = 0.004) but not with RA susceptibility.
Conclusions
These results confirm that the IL‐17A ‐737T/C, ‐444A/G, ‐197G/A, and ‐121G/A SNPs are not risk factors for RA, but the IL‐17A TAGA haplotype is a risk factor for SLE. This is the first report to document an association between IL‐17A and SLE susceptibility in adults.