Nucleotide numbering

Last modified February 10, 2011

Since references to WWW-sites are not yet acknowledged as citations, please mention den Dunnen JT and Antonarakis SE (2000). Hum.Mutat. 15:7-12 when referring to these pages.

Genomic reference sequences

For genomic reference sequences, nucleotide numbering is simple 1, 2, 3, ....etc. from the first to the last nucleotide of the reference seqence. No "+", "-" or other signs are used (see xxxDiscussion).

Coding DNA reference sequences

In a coding DNA reference sequence nucleotide "1" is the A of the ATG translation initiation codon. The main reason why most people prefer a coding DNA reference sequence is that from the description one immediately gets some information regarding the location of the variant; 

Dividing the nucleotide number by 3 gives the number of the amino acid residue affected, in the example amino acid 26 (78:3 = 26).

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