Is BAG3 p.Arg203Pro (c.608G>C) pathogenic?

BAG3 p.Arg203Pro (c.608G>C) is classified Uncertain significance in BAG3 (ClinVar, Multiple submitters, 2 submitters; last evaluated 2025-05-12). AlphaMissense: likely benign (0.2768); Very rare (popmax 0.00167%, amr); Associated with myofibrillar myopathy 6.

What condition is associated with BAG3 p.Arg203Pro (c.608G>C)?

BAG3 p.Arg203Pro (c.608G>C) is associated with myofibrillar myopathy 6, dilated cardiomyopathy 1HH (ClinVar).

How common is BAG3 p.Arg203Pro (c.608G>C) in the general population?

BAG3 p.Arg203Pro (c.608G>C) is very rare (popmax 0.00167%, amr) (gnomAD).

How is BAG3-related myofibrillar myopathy inherited?

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

What do computational predictors say about BAG3 p.Arg203Pro (c.608G>C)?

AlphaMissense predicts likely benign (score 0.2768) — an in-silico prediction, not a clinical call.

BAG3 p.Arg203Pro

c.608G>C · rs1057524225 · VCV1053859

Uncertain significance Multiple submitters

Classification

Uncertain significance

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 2 submitters

AlphaMissense

likely benign

0.2768 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.00167%, amr)

Missense predictors

0/2 damaging

AlphaMissense, SaProt · REVEL no call

Conditions

myofibrillar myopathy 6

Computational evidence

Protein change
AlphaMissense	0.2768	likely benign
REVEL	0.476	indeterminate
SaProt	LLR -0.06	tolerated
⇒ AlphaMissense and SaProt both call this tolerated; REVEL makes no call.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 12	GERP 2.4, phastCons 1
Regional constraint	o/e 1.04	unconstrained · MANE · 26 kb · p 0.29 · regional, not allelic
Overall
CADD	23.3	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 and SaProt are independent agreement signals.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00167% Admixed American · 1/60,000 alleles

Overall 0.000124% 2/1,613,960 alleles · very rare

Ancestry group	Frequency	1 in
Admixed Americangrpmax	0.00167%	60,000
European (non-Finnish)	8.47e-05%	1,180,020

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: BAG3
Protein: p.Arg203Pro
Coding: c.608G>C
MANE Select: NM_004281
dbSNP: rs1057524225
Type: single nucleotide variant
Location: chr10:119672355 (GRCh38)
Gene constraint: LOEUF 0.538 · pLI 0.92 · ClinGen HI 3/3 (gnomAD)
Structure: AlphaFold pLDDT 57.98

Full BAG3 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

myofibrillar myopathy 6 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: dilated cardiomyopathy 1HH

For BAG3-related myofibrillar myopathy (Orphanet):

Inheritance: Autosomal dominant
Onset: Adolescent, Childhood

Similar variants

BAG3 p.Arg203Gln Uncertain significance ★★ ⚠ same residue
BAG3 p.Arg203Trp Uncertain significance ★★ ⚠ same residue
BAG3 p.Arg203= Likely benign ★ same residue
BAG3 p.Arg203fs Pathogenic ★★ same residue
BAG3 p.Arg121Ter Pathogenic/Likely pathogenic ★★ same condition
BAG3 p.Arg123Ter Pathogenic/Likely pathogenic ★★ same condition
BAG3 p.Arg309Ter Pathogenic ★★ same condition
BAG3 p.Arg473Ter Pathogenic/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/bag3-p-arg203pro (accessed [today's date]).

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