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Adam MP, Mirzaa GM, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2023.

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GeneReviews® [Internet].

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Appendix: Quick Reference

Initial Posting: ; Last Update: January 31, 2019.

Estimated reading time: 1 minute

Naming Conventions

Standard nomenclature for DNA and protein amino acid sequence. GeneReviews uses the nomenclature guidelines at varnomen.hgvs.org. If the standard nomenclature for a sequence variant cannot be determined, the variant is designated as an alias and a reference to the earliest reported description of the variant is provided.

Table 1.

Basic structure for DNA and Protein Amino Acid Sequence Nomenclature

PrefixType of Sequence from which the Number(s) are DerivedExampleInterpretationCommonly Describes
c.coding DNA sequence, where nucleotide #1 is the first nucleotide of the first codonc.535T>CThe T at nucleotide number 535 of the coding region changed to a C.Nucleotide changes in genes (exons, splice sites, untranslated regions)
p.protein amino acid sequence, where #1 is the first amino acid residue of the proteinp.Cys179ArgThe cysteine amino acid at residue 179 changed to an arginine.Amino acid changes in a protein
g.genomic DNA sequence, where #1 is the first nucleotide in a given reference sequenceg.66781T>CThe T at nucleotide 66781 in the genomic reference sequence changed to a C.Nucleotide changes in introns, regulatory, and intergenic regions
m.mitochondrial DNA sequence, where #1 is the first nucleotide in the sequence of the entire mitochondrion genomem.8994T>CThe T at nucleotide 8994 of the mitochondrial genome changed to a C.Coding and non-coding variants of mitochondrial genome

Reference sequence. For the variant nomenclature to be valid, a reference sequence is required. Reference sequences are found at www.ncbi.nlm.nih.gov. Note:

  • Reference sequences beginning with "NM" refer to coding nucleotide sequences and those beginning with "NP" refer to protein sequences.
  • Genes may have multiple reference sequences. The reference sequence shown in the GeneReview matches the exon structure and reference used by the majority of citations.

Abbreviations for amino acids. GeneReviews standard is use of the 3-letter symbol for amino acids.

Table 2.

Amino Acid Abbreviations

Aspartic acidAspD
Glutamic acidGluE
stop codonTer 1



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Bookshelf ID: NBK1528


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