identify specific binding locations within mRNAs but not the miRNAs that bind to the locations. Therefore, these experiments still required predictions based on sequence complementarity to determine either the specific binding location or the binding miRNA. In contrast, a recent advance in the high-throughput direct mapping of miRNA–mRNA binding sites from CLASH (cross linking, ligation and sequencing of hybrids) (25,26) experiments identifies both the miRNA and mRNA sequence simultaneously and presents the opportunity to identify polymorphisms in miRNA binding sites where both miRNAs and their binding sites are determined from the experiment. The newly available experimental data for miRNA–mRNA interactions and other rapidly growing genomic data allow us to perform a major update of the PolymiRTS database and make it a more useful and complete resource for linking polymorphic miRNA targeting to complex traits, diseases and biological pathways.
