We have expanded the PolymiRTS database with updated data and enhanced the database with new features, which include the following: CLASH experiment data. CLASH is a new technique for high-throughput mapping of RNA–RNA interactions (25) that have recently been used for direct identification of miRNA–mRNA target pairs associated with human AGO1 protein (26), a component of the miRNA-induced silencing complex (miRISC). While previous methods for high-throughput identification of miRNA target sites (e.g. PAR-CLIP) identified only target site sequences and, then, relied on computational scans for complementary miRNA seeds to predict the targeting miRNAs, CLASH provides chimeric reads of miRNA and target site sequences and, therefore, directly identifies the binding miRNA and allows for improved determination of noncanonical miRNA–mRNA interactions, which involve bulged or mismatched nucleotides. The CLASH data set included in current PolymiRTS database contains 18 514 high confidence canonical and noncanonical target sites of 399 human miRNAs.INDELs in miRNA sequences and miRNA target sites. About 18% of known human genetic variants are INDELs (27,28), constituting the second largest class of genetic variants after SNPs. Currently, >400 000 small INDELs
