Is HTT p.Arg3128Trp (c.9382C>T) pathogenic?

HTT p.Arg3128Trp (c.9382C>T) is classified Uncertain significance in HTT (ClinVar, Single submitter, 1 submitter; last evaluated 2022-12-02). AlphaMissense: likely benign (0.1167); Very rare (popmax 0.00187%, nfe).

How common is HTT p.Arg3128Trp (c.9382C>T) in the general population?

HTT p.Arg3128Trp (c.9382C>T) is very rare (popmax 0.00187%, nfe) (gnomAD).

What do computational predictors say about HTT p.Arg3128Trp (c.9382C>T)?

AlphaMissense predicts likely benign (score 0.1167) — an in-silico prediction, not a clinical call.

HTT p.Arg3128Trp

c.9382C>T · rs769006451 · VCV1366273

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely benign

0.1167 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.00187%, nfe)

Missense predictors

0/2 damaging

AlphaMissense, REVEL · SaProt no call

Computational evidence

Protein change
AlphaMissense	0.1167	likely benign
REVEL	0.192	benign-leaning
SaProt	—	not scored · why
⇒ AlphaMissense and REVEL both call this tolerated; SaProt makes no call.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 2.8	GERP -0.063, phastCons 1
Overall
CADD	26.7	PHRED · no single calibrated threshold — expert panels disagree

ClinVar classifies this uncertain; the computational predictors unanimously lean tolerated — a triage signal, not a reclassification

AlphaMissense carries the ACMG weight for missense; REVEL is an independent agreement signal.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00187% European (non-Finnish) · 22/1,173,568 alleles

Filtering AF 0.00123% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00105%

Overall 0.00144% 23/1,601,056 alleles · very rare

Ancestry group	Frequency	1 in
European (non-Finnish)grpmax	0.00187%	53,344
South Asian	0.00113%	88,442

Rarity supports pathogenicity (ACMG PM2); frequency above a disease-specific BA1/BS1 threshold argues against it. A variant frequent in one ancestry group can be near-absent in others, so a single global figure can mislead.

Variant & gene context

Gene: HTT
Protein: p.Arg3128Trp
Coding: c.9382C>T
MANE Select: NM_001388492
dbSNP: rs769006451
Type: single nucleotide variant
Location: chr4:3240012 (GRCh38)
Structure: AlphaFold pLDDT 85.38 · 30 PDB

Full HTT gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Similar variants

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HTT p.Arg1654Trp Uncertain significance ★★ same type
HTT p.Arg1945Trp Uncertain significance ★★ same type
HTT p.Asp1157Gly Uncertain significance ★★ same type
HTT p.Asp920Asn Uncertain significance ★★ same type
HTT p.Glu449Ala Uncertain significance ★★ ⚠ same type
HTT p.Gly2084Arg Uncertain significance ★★ same type

Built on 18 open, versioned datasets — ClinVar, gnomAD, AlphaMissense, REVEL, ClinGen & more — plus Sugi Variant's own cross-source analysis. Source data 2026-01–2026-10, ClinVar 2026-10. Full sources & versions →

Cite Sugi Variant

Gür T. Sugi Variant: A Deterministic Per-Variant Germline Reference from a Knowledge Graph for Humans and AI Agents. 2026. doi:10.5281/zenodo.21509445. This variant: https://sugi.bio/variant/htt-p-arg3128trp (accessed [today's date]).

Preprint & method: sugi.bio/variant/method Machine-readable: this page as Markdown