miRNA Nomenclature: A View Incorporating Genetic Origins, Biosynthetic Pathways, and Sequence Variants

Trends Genet. 2015 Nov;31(11):613-626. doi: 10.1016/j.tig.2015.09.002. Epub 2015 Oct 8.


High-throughput sequencing of miRNAs has revealed the diversity and variability of mature and functional short noncoding RNAs, including their genomic origins, biogenesis pathways, sequence variability, and newly identified products such as miRNA-offset RNAs (moRs). Here we review known cases of alternative mature miRNA-like RNA fragments and propose a revised definition of miRNAs to encompass this diversity. We then review nomenclature guidelines for miRNAs and propose to extend nomenclature conventions to align with those for protein-coding genes established by international consortia. Finally, we suggest a system to encompass the full complexity of sequence variations (i.e., isomiRs) in the analysis of small RNA sequencing experiments.

Keywords: isomiR; loop-origin miRNAs; miRNA cluster; miRNA-seq; moR; noncoding RNA.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Biosynthetic Pathways / genetics*
  • DEAD-box RNA Helicases / genetics
  • DEAD-box RNA Helicases / metabolism
  • Gene Expression Regulation
  • Genetic Variation*
  • Humans
  • Mice
  • MicroRNAs / classification*
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism
  • RNA, Small Cytoplasmic / genetics
  • RNA, Small Cytoplasmic / metabolism
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism
  • Ribonuclease III / genetics
  • Ribonuclease III / metabolism
  • Sequence Analysis, RNA
  • Terminology as Topic*
  • Transcriptome
  • Zebrafish


  • MicroRNAs
  • RNA, Small Cytoplasmic
  • RNA, Small Interfering
  • Dicer1 protein, mouse
  • Drosha protein, mouse
  • Ribonuclease III
  • DEAD-box RNA Helicases