Sequence Variant Descriptions: HGVS Nomenclature and Mutalyzer.

Consistent and unambiguous description of sequence variants is essential to report and exchange information on the analysis of a genome, in particular in DNA diagnostics. The HGVS nomenclature-recommendations for the description of sequence variants as originally proposed by the Human Genome Variation Society-has gradually been accepted as the international standard for variant description. In this unit, we describe the current recommendations (HGVS version 15.11) regarding how to describe variants at the DNA, RNA, and protein level. We explain the rationale and give example descriptions for all variant types: substitution, deletion, duplication, insertion, inversion, conversion, and complex, as well as special types occurring only on the RNA (splicing) or protein level (nonsense, frame shift, extension). Finally, we point users to available support tools and give examples for the use of the freely available Mutalyzer suite. An extensive version of the HGVS recommendations is available online at http://varnomen.hgvs.org/. © 2016 by John Wiley & Sons, Inc.