The functional importance of small RNA is first described

Functionally important small RNA were first described in nematodes and published December 3, 1993. This begins the scientific understanding that not all RNA codes for a protein.  It was not until 2001 that the functionality of micro RNA (miRNA), which are noncoding small RNA 18 to 26 nucleotides (nt) long, were understood, and to not be just confinded to the lower orders. [1, 2]

It was in 2005 that the regulatory function of miRNA’s begins to emerge.  Gene expression is regulated by these non-coding miRNA’s, which in turn help regulate biological pathways – such as the immune system.  This emerging field of gene regulation is know as epigenetics. [3]