RNA Recommendations

Deletion Variant


a sequence change where, compared to a reference sequence, one or more nucleotides are not present (deleted).


Format: “prefix”“position(s)_deleted”“del”, e.g. r.123_127del

“prefix” = reference sequence used = r.
“position(s)_deleted” = position nucleotide or range of nucleotides deleted = 123_127
“del” = type of change is a deletion = del


  • prefix reference sequences accepted are r. (coding and non-coding RNA).
  • the “position(s)_deleted” should contain two different positions, e.g. 123_126 but not 123_123.
  • the “position(s)_deleted” should be listed from 5’ to 3’, e.g. 123_126 but not 126_123.
  • for all descriptions the most 3’ position possible of the reference sequence is arbitrarily assigned to have been changed (3’rule)
    • the 3’rule also applies for changes in single residue stretches and tandem repeats (nucleotide or amino acid)
    • the 3’rule applies to ALL descriptions (genome, gene, transcript and protein) of a given variant


  • r.7del (one nucleotide)
    a deletion of the “u” at position r.7 in the sequence “auguacugcc to “auguac_gcc”
    NOTE: it is allowed to describe the variant as r.7delu
  • r.6_8del (several nucleotides)
    a deletion of nucleotides r.6 to r.8 in the sequence “augauugcc” to “augau___c
    NOTE: it is allowed to describe the variant as r.6_8delugc
  • r.(4072_5145)del
    the predicted deletion of exon 30 (starting at position r.4072) to exon 36 (ending at position r.5145) of the DMD-gene; RNA has not been analysed.


Can I use r.123del6 to describe a 6 nucleotide deletion?

No, a deletion of more than one residue should mention the first and last residue deleted, separated using the range symbol ("_", underscore), e.g. r.123_128del and not r.123del6.

Is the description of a deletion of exon 17 as r.EX17del still allowed?

A description like r.EX17del has never been allowed. Descriptions should be specific and indicate the nucleotides affected by the change.