miRNAs and related polymorphisms in rheumatoid arthritis susceptibility.

The epigenetic mechanisms in regulation of genes' expression seem to be another field of research that gains land in genetic association studies of rheumatoid arthritis (RA) susceptibility factors. Recently, a new class of molecules has been discovered, the microRNAs (miRNAs). miRNAs are related to post-transcriptional regulation of genes' expression. Different expression patterns of mir-146a, miRNA-155, miRNA-124a, mir-203, mir-223, mir-346, mir-132, mir-363, mir-498, mir-15a, and mir-16 were documented in several tissue sample types of RA patients. The polymorphisms of these miRNAs and their gene targets, which previously have been associated with RA or other autoimmune diseases, are also reviewed. Finally, using web-based tools we propose polymorphisms of the discussed miRNAs and their gene-targets that worth to be studied for their role in RA predisposition.