Micro RNAs are

MicroRNAs (miRNAs) are small noncoding RNAs 20-22 nucleotides in length that are involved in posttranscriptional gene regulation. Studies in chronic lymphocytic leukaemia first suggested a link between miRNAs and cancer when miR-15 and miR-16 were found to be deleted or downregulated in the vast majority of tumours.The expression of miRNAs is extremely specific and there is evidence that miRNA expression patterns may be useful in distinguishing lineage and differentiation state, as well as cancer diagnosis and outcome prediction.Reference: Harrison; 19th edition