HGVS of tandem repeats

[Lucy Eng]

Hello,

The guidance on the website (https://hgvs-nomenclature.org/stable/recommendations/DNA/repeated/) lists an example of the gene HTT where the HGVS nomenclature of the repeat expansion used the 3' rule. However, in a presentation by a HGVS representative to the ClinGen Biocurator team in 2019 (Minute 31 in the video recording https://www.youtube.com/watch?v=PaUxUzIdLaM). He stated that the nomenclature of repeat expansion should use the starting position of the first repeat and not use the 3' rule. Has this rule been changed since 2019? Can you clarify the discrepancy?

I am trying to find the best way to name a repeat expansion in the gene ATN1 NM_001940.4, in which exon 5 has tandem repeat of glutamine residues starting at p.484.  

Regards,

Lucy S. Eng, M.S.

Senior Biocurator, ClinGen-affiliated UNC

Biocuration and Coordination Core

Department of Genetics

University of North Carolina at Chapel Hill

Lucy...@med.unc.edu

 

[Johan den Dunnen]

Dear Lucy,

the guidance on the website (https://hgvs-nomenclature.org/stable/recommendations/DNA/repeated/) is correct. The 3' rule also applies for variants in repeat expansions. The rule has never changed.

Best regards,

Johan den Dunnen
HUGO HGVS Variant Nomenclature Committee (HVNC)

Op donderdag 7 mei 2026 om 23:12:44 UTC+2 schreef eng.l...@gmail.com: