Potential contribution of miRNAs to the pathogenesis of CAG repeat-dependent SCAs. A) The schematic presentation of the CAG expansion in the ATXN genes and CAG expansion-induced toxicity factors. B) The graphical presentation of the 3′-UTRs of SCA disease-causing genes. Grey rectangles represent appropriate 3′-UTRs. Their length is delineated and a scale of 1,000 nt is shown. Black numbers indicate the number of sites for miRNA families broadly conserved among vertebrates predicted by the TargetScanHuman algorithm (Release 6.2) . Green numbers show the number of validated miRNA-target interactions collected in the miRTarBase (Release 4.5) ; bold green numbers and unbolded ones denote the number of interactions validated by methods providing strong and less strong evidence, respectively. C) Mechanisms of miRNA-mediated control of gene expression. The main regulatory activities of miRNAs and global deregulation of multiple genes are schematically presented. Additionally, essential methods used for validation of miRNA-mRNA interactions are listed.