MicroRNA-New Category of Diagnostic Biomarkers

MicroRNAs (miRNA) are small (21-24 nucleotides) noncoding RNAs which are involved in negative posttranscriptional regulation of gene expression. One miRNA molecule can have up to hundreds of target mRNAs and one mRNA can be regulated by multiple miRNAs, creating a complex regulatory network in the body/organism [1].Changes in intracellular miRNA levels affect gene expression, alter cell signaling, and significantly affect cellular metabolism. They regulate physiological processes including cell differentiation, regeneration and apoptosis, as well as pathological processes such as neoplastic transformation of cells. Therefore, it is not surprising that aberrant miRNA expression is involved in the pathogenesis of many diseases including cardiovascular diseases, neurodegenerative diseases and cancer. To this day, more than 2,500 different microRNAs have been described in various documents [2-7].