The IRAK1 and miR-499 polymorphisms play an important role in the etiology of rheumatoid arthritis (RA). Several studies have been carried out to estimate the association between IRAK1 rs3027898 and miR-499 rs3746444 and RA risk; however, the results were inconsistent.
A case control study was carried out to explore the association between IRAK1 rs3027898 and miR-499 rs3746444 and the RA risk in a Chinese population. Meta-analyses combining present with previous studies were conducted to further explore the association.
A total of 386 RA patients were enrolled along with 576 matched healthy controls. Genotyping was performed by using TaqMan genotyping assays on Fluidigm 192.24 system. For the meta-analysis, a systematic literature search was conducted to identify all relevant studies.
This case control study showed that the IRAK1 rs3027898 C allele was associated with increased risk of RA with an odds ratio (OR) = 1.4 and 95 % confidence intervals (CI) = 1.093-1.793, P = 0.008 but miR-499 rs3746444 polymorphisms were not significantly associated with the risk for RA. The meta-analyses included a total of 4 case control studies on IRAK1 rs3027898 and 4 studies on miR-499 rs3746444. The IRAK1 rs3027898 C allele had an overall OR of 1.268 (95 % CI = 1.130-1.424, P < 0.001). After stratification by ethnicity the C allele had an OR of 1.238 (95 % CI = 1.096-1.398, P = 0.001) in Asians. No association between miR-499 rs3746444 polymorphism and RA was found in the overall and Asian populations.
The results from our case control study and the meta-analyses indicate that the IRAK1 rs3027898 C allele is significantly associated with an increased risk of RA, especially in Asians.