Is ACTN3 p.Tyr255Cys (c.764A>G) pathogenic?

ACTN3 p.Tyr255Cys (c.764A>G) is classified Uncertain significance in ACTN3 (ClinVar, Single submitter, 1 submitter; last evaluated 2025-10-08). AlphaMissense: likely pathogenic (0.9245); Ultra-rare (popmax 0.0131%, nfe).

How common is ACTN3 p.Tyr255Cys (c.764A>G) in the general population?

ACTN3 p.Tyr255Cys (c.764A>G) is ultra-rare (popmax 0.0131%, nfe) (gnomAD).

What do computational predictors say about ACTN3 p.Tyr255Cys (c.764A>G)?

AlphaMissense predicts likely pathogenic (score 0.9245) — an in-silico prediction, not a clinical call.

ACTN3 p.Tyr255Cys

c.764A>G · rs368334575 · VCV2592823

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely pathogenic

0.9245 · ACMG-weighted

gnomAD v4.1

Rare

ultra-rare (popmax 0.0131%, nfe)

Missense predictors

2/2 damaging

AlphaMissense, SaProt

Computational evidence

Protein change
AlphaMissense	0.9245	likely pathogenic
SaProt	LLR -14.80	damaging
⇒ AlphaMissense and SaProt both call this damaging.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 9.3	GERP 2.5, phastCons 1
Regional constraint	o/e 1.04	unconstrained · MANE · 7,830 bp · p 0.26 · regional, not allelic
Overall
CADD	27.4	PHRED · no single calibrated threshold — expert panels disagree

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

AlphaMissense carries the ACMG weight for missense; REVEL and SaProt are independent agreement signals.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.0131% European (non-Finnish) · 155/1,179,938 alleles

Filtering AF 0.0114% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.0107%

Overall 0.01% 162/1,613,816 alleles · ultra-rare

Ancestry group	Frequency	1 in
European (non-Finnish)grpmax	0.0131%	7,612
Remaining individualsnot grpmax-eligible	0.008%	12,493
African / African-American	0.00267%	37,464

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: ACTN3
Protein: p.Tyr255Cys
Coding: c.764A>G
MANE Select: NM_001104
dbSNP: rs368334575
Type: single nucleotide variant
Location: chr11:66556190 (GRCh38)
Gene constraint: LOEUF 0.944 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 84.61 · 3 PDB
Residue 255: the calponin-homology (ch) 2 domain; an α-helix; the 'actin-binding' region

Full ACTN3 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Similar variants

ACTN3 p.Ala115Asp Uncertain significance ★ ⚠ same type
ACTN3 p.Ala149Thr Uncertain significance ★ ⚠ same type
ACTN3 p.Ala251Thr Uncertain significance ★ ⚠ same type
ACTN3 p.Ala410Pro Uncertain significance ★ ⚠ same type
ACTN3 p.Ala410Val Uncertain significance ★ ⚠ same type
ACTN3 p.Ala460Val Uncertain significance ★ ⚠ same type
ACTN3 p.Ala469Gly Uncertain significance ★ ⚠ same type
ACTN3 p.Ala470Pro 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/actn3-p-tyr255cys (accessed [today's date]).

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