Is ACTC1 p.Arg256Pro (c.767G>C) pathogenic?

ACTC1 p.Arg256Pro (c.767G>C) is classified Uncertain significance in ACTC1 (ClinVar, Single submitter, 1 submitter; last evaluated 2024-04-24). AlphaMissense: likely pathogenic (0.9989); Absent from gnomAD v4.1; Associated with atrial septal defect 5.

What condition is associated with ACTC1 p.Arg256Pro (c.767G>C)?

ACTC1 p.Arg256Pro (c.767G>C) is associated with atrial septal defect 5, hypertrophic cardiomyopathy 11, dilated cardiomyopathy 1R (ClinVar).

How common is ACTC1 p.Arg256Pro (c.767G>C) in the general population?

ACTC1 p.Arg256Pro (c.767G>C) is absent from gnomAD v4.1 (gnomAD).

What do computational predictors say about ACTC1 p.Arg256Pro (c.767G>C)?

AlphaMissense predicts likely pathogenic (score 0.9989) — an in-silico prediction, not a clinical call.

ACTC1 p.Arg256Pro

c.767G>C · VCV3755985

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely pathogenic

0.9989 · ACMG-weighted

gnomAD v4.1

Absent

absent from gnomAD v4.1

Missense predictors

3/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

atrial septal defect 5

Computational evidence

Protein change
AlphaMissense	0.9989	likely pathogenic · top 10% in ACTC1
REVEL	0.941	strongly pathogenic-leaning
SaProt	LLR -13.13	damaging
⇒ AlphaMissense, REVEL and SaProt all call this damaging.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 7.7	GERP 2.3, phastCons 1
Regional constraint	o/e 0.16	constrained · MANE · 2,113 bp · p 8.3e-37 · regional, not allelic
Overall
CADD	31.0	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

Absent from gnomAD v4.1. Not observed in any sequenced alleles — a rarity signal (ACMG PM2-supporting), not evidence of pathogenicity on its own.

Variant & gene context

Gene: ACTC1
Protein: p.Arg256Pro
Coding: c.767G>C
MANE Select: NM_005159
Type: single nucleotide variant
Location: chr15:34792131 (GRCh38)
Gene constraint: LOEUF 0.511 · pLI 0.97 · ClinGen HI 1/3 (gnomAD)
Structure: AlphaFold pLDDT 95.47 · 16 PDB
Residue 256: an α-helix

Full ACTC1 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

atrial septal defect 5 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: hypertrophic cardiomyopathy 11 dilated cardiomyopathy 1R

Similar variants

ACTC1 p.Arg256= Likely benign ★★ same residue
ACTC1 p.Glu101Lys Pathogenic ★★★ same condition
ACTC1 p.Val56Ile Uncertain significance ★★★ ⚠ same condition
ACTC1 p.Ala297Ser Pathogenic ★★ ⚠ same condition
ACTC1 p.Gly247Asp Pathogenic/Likely pathogenic ★★ same condition
ACTC1 p.Thr128Ile Likely pathogenic ★★ same condition
ACTC1 c.455-6G>A Uncertain significance ★★ same condition
ACTC1 c.808+1G>C Uncertain significance ★★ same condition

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/actc1-p-arg256pro (accessed [today's date]).

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