Ter: number of amino acids

Anna Matys

unread,

Jun 23, 2026, 7:21:13 AMJun 23

to HGVS Nomenclature

Dear HGVS team,

how many amino acids does the protein with the mutation p.(Gln1756ProfsTer74) contain?

Is it 1756 + 74 (so 1830) or 1756 + 73 (so 1829) because the last position is termination and there is no specific amino acid that would terminate the synthesis?

Best regards,

Anna

Johan den Dunnen

unread,

Jun 25, 2026, 8:46:13 AMJun 25

to HGVS Nomenclature

Dear Anna,

p.(Gln1756ProfsTer74) means the predicted consequences of a variant (which you do not give but is mandatory to report) contains a Ter codon at position 74 of the shifted reading frame. The protein therefor is translated into 1756 + 73 = 1829 amino acids. Modification of the mature protein may remove additional amino acids, starting with the Met at position1.

Best regards,

Johan den Dunnen
HUGO HGVS Variant Nomenclature Committee (HVNC)

Op dinsdag 23 juni 2026 om 13:21:13 UTC+2 schreef Anna Matys:

Scott McMahan

unread,

Jun 25, 2026, 12:22:28 PMJun 25

to Johan den Dunnen, HGVS Nomenclature

My reading of the rule is that the initial translation produces an 1828 amino acid protein since 1756 is the first position of the first new amino acid. So we have 1755 amino acids that match reference sequence + 73 shifted frame amino acids + termination at fs position 74. If that is incorrect, then the notes at Frameshift - HGVS Nomenclature should clarify further.

From: hgvs-nom...@googlegroups.com <hgvs-nom...@googlegroups.com> On Behalf Of Johan den Dunnen
Sent: Thursday, June 25, 2026 7:46 AM
To: HGVS Nomenclature <hgvs-nom...@googlegroups.com>
Subject: [hgvs-nomenclature] Re: Ter: number of amino acids

External Mail. Careful of links / attachments. Submit Helpdesk if unsure.

--
You received this message because you are subscribed to the Google Groups "HGVS Nomenclature" group.
To unsubscribe from this group and stop receiving emails from it, send an email to hgvs-nomenclat...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/hgvs-nomenclature/b461ed2e-7fe0-4d16-ae3b-b9dbdd0304c2n%40googlegroups.com.

Raymond Dalgleish

unread,

Jun 27, 2026, 7:00:46 AMJun 27

to HGVS Nomenclature

I am intrigued by your question " how many amino acids does the protein with the mutation p.(Gln1756ProfsTer74) contain?"

A premature termination codon will, in most cases, trigger nonsense mediate decay (NMD) of the variant transcript resulting in no protein being produced at all.

Johan den Dunnen

unread,

Jul 8, 2026, 4:21:06 AMJul 8

to HGVS Nomenclature

Dear Ana,

sorry, I made a mistake, correct should be "The protein therefor is translated into 1755 + 73 = 1828 amino acids."