Polymorphisms in miRNA genes and their involvement in autoimmune diseases susceptibility

MicroRNAs (miRNAs) are small non-coding RNA molecules that negatively regulate the expression of multiple protein-encoding genes at the post-transcriptional level. MicroRNAs are involved in different pathways, such as cellular proliferation and differentiation, signal transduction and inflammation, and play crucial roles in the development of several diseases, such as cancer, diabetes, and cardiovascular diseases. They have recently been recognized to play a role also in the pathogenesis of autoimmune diseases. Although the majority of studies are focused on miRNA expression profiles investigation, a growing number of studies have been investigating the role of polymorphisms in miRNA genes in the autoimmune diseases development. Indeed, polymorphisms affecting the miRNA genes can modify the set of targets they regulate or the maturation efficiency. This review is aimed to give an overview about the available studies that have investigated the association of miRNA gene polymorphisms with the susceptibility to various autoimmune diseases and to their clinical phenotypes.