MiR-146a (rs2910164) Gene Polymorphism and Its Impact on Circulating MiR-146a Levels in Patients with Inflammatory Bowel Diseases

MicroRNA-146a (miR-146a) has been involved in the pathophysiology of inflammatory bowel disease (IBD). However, the precise processes are still not entirely understood. Contradictory studies suggest that miR-146a expression could be influenced by the miR-146a rs2910164 C > G polymorphism. This case-control study aimed to investigate the association of miR-146a rs2910164 C > G gene polymorphism and its impact on circulating miR-146a expression levels in Egyptian IBD patients. We included 40 IBD patients and 30 matched healthy controls. Genotyping of miR-146a rs2910164 polymorphism and assessment of miR-146a expression level were done using quantitative real-time PCR in all participants. MiR-146a rs2910164 GG genotype and the G allele were reported in 47% and 70% of the IBD patient group, respectively. And they were associated with increased IBD risk. All the IBD patients with the CC genotype (100%) and most of those with the CG genotype (66.67%) had an inactive disease, while most IBD patients with the GG genotype (73.68%) had an active disease. The miR-146a expression level was the highest with the CC genotype and the lowest with the GG genotype. Also, miR-146a expression level decreased significantly in IBD patients than controls and with disease activity. Combined detection of fecal calprotectin with miR-146a expression level improved the diagnostic sensitivity and the negative predictive value in differentiating IBD patients with active disease from those inactive. Our study identified a strong association of miR-146a rs2910164 GG genotype and G allele with IBD-increased susceptibility and activity in the Egyptian population. The miR-146a rs2910164 polymorphism can reduce miR-146a expression levels in these patients as well. Further research on a larger sample size and different ethnic populations can be the key to progress in establishing this genetic association.