Is ACTA1 p.Ala183= (c.549G>A) pathogenic?

ACTA1 p.Ala183= (c.549G>A) is classified Benign/Likely benign in ACTA1 (ClinVar, Multiple submitters, 5 submitters; last evaluated 2026-01-26). Low-frequency (popmax 1.27%, eas); Associated with congenital fiber-type disproportion myopathy.

What condition is associated with ACTA1 p.Ala183= (c.549G>A)?

ACTA1 p.Ala183= (c.549G>A) is associated with congenital fiber-type disproportion myopathy, congenital myopathy 2a, typical, autosomal dominant, familial restrictive cardiomyopathy (ClinVar).

How common is ACTA1 p.Ala183= (c.549G>A) in the general population?

ACTA1 p.Ala183= (c.549G>A) is low-frequency (popmax 1.27%, eas) (gnomAD).

How is Congenital fiber-type disproportion myopathy inherited?

Typically Autosomal dominant, Autosomal recessive (Orphanet). A genetic counselor can assess individual risk for a family.

ACTA1 p.Ala183=

c.549G>A · rs200094415 · VCV296056

Benign/Likely benign Multiple submitters

Classification

Benign/Likely benign

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 5 submitters

gnomAD v4.1

Rare

low-frequency (popmax 1.27%, eas)

Conditions

congenital fiber-type disproportion myopathy

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP -6.7	GERP -5.2
Overall
CADD	1.262	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 1.27% East Asian · 570/44,860 alleles

Filtering AF 1.18% ClinGen BA1/BS1 input FAF95, joint · FAF99 1.15%

Overall 0.0471% 760/1,613,764 alleles · low-frequency

Ancestry group	Frequency	1 in
East Asiangrpmax	1.27%	79
South Asian	0.105%	949
Remaining individualsnot grpmax-eligible	0.0704%	1,420
Middle Eastern	0.0495%	2,020
European (non-Finnish)	0.00381%	26,219
Admixed American	0.00167%	60,008
African / African-American	0.00133%	75,008

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: ACTA1
Protein: p.Ala183=
Coding: c.549G>A
MANE Select: NM_001100
dbSNP: rs200094415
Type: single nucleotide variant
Location: chr1:229432337 (GRCh38)
Gene constraint: LOEUF 0.931 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 95.21 · 5 PDB

Full ACTA1 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

congenital fiber-type disproportion myopathy — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: congenital myopathy 2a, typical, autosomal dominant familial restrictive cardiomyopathy

For Congenital fiber-type disproportion myopathy (Orphanet):

Inheritance: Autosomal dominant, Autosomal recessive, X-linked recessive
Onset: Infancy, Neonatal

Similar variants

ACTA1 p.Ala183Pro Uncertain significance ⚠ same residue
ACTA1 p.Ala183Thr Pathogenic ★ same residue
ACTA1 c.617-5C>A Likely pathogenic ★★★ same condition
ACTA1 c.990+1G>T Pathogenic ★★★ same condition
ACTA1 p.Asp13Asn Likely pathogenic ★★★ same condition
ACTA1 p.Asp290His Pathogenic ★★★ same condition
ACTA1 p.Asp58Asn Likely pathogenic ★★★ same condition
ACTA1 p.Cys376Phe Likely pathogenic ★★★ 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/acta1-p-ala183 (accessed [today's date]).

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