MicroRNA (abbreviated miRNA) is a small non-coding RNA molecule (containing about 22 nucleotides) found in plants, animals and some viruses, that functions in RNA silencing and post-transcriptional regulation of gene expression. While the majority of miRNAs are located within the cell, some miRNAs, commonly known as circulating miRNAs or extracellular miRNAs, have also been found in extracellular environment, including various biological fluids and cell culture media.

Dra. Eman Refaat Youness, doctora en Bioquímica Médica, Facultad de Medicina, Universidad de El Cairo, profesora adjunta de Bioquímica Médica, Centro Nacional de Investigación, Egipto, con experiencia en diseño experimental, investigaciones clínicas, numerosas publicaciones internacionales, miembro de sociedades internacionales, revisora y editora de numerosas revistas.