MicroRNAs (miRNAs) are small non-coding RNA molecules of approximately 22-24 nucleotides in length involved in the post-transcriptional regulation of gene expression. Depending on their sequence, they are able to specifically target mRNAs and repress their translation. As mediators of post-transcriptional regulation, miRNAs play an important role in various cellular processes, such as proliferation, differentiation and apoptosis but have also been associated with tumourigenesis. The miR-371-3 cluster is located in close vicinity to another miRNA cluster, namely C19MC (chromosome 19 miRNA cluster). C19MC consists of 46 miRNA genes encoding for 62 mature miRNAs. All mature miRNAs of C19MC are apparently processed from one large non-protein-coding polymerase II transcript. Embryonal tumor with multilayered rosettes is an aggressive embryonal tumors arise in infants throughout the central nervous system, sharing a genetic signature unique to this group, namely, amplification involving a cluster of microRNAs termed C19MC.