Is CHAT p.Arg28= (c.84G>A) pathogenic?

CHAT p.Arg28= (c.84G>A) is classified Likely benign in CHAT (ClinVar, Single submitter, 1 submitter; last evaluated 2023-02-11). Very rare (popmax 8.72e-05%, nfe); Associated with congenital myasthenic syndrome 6.

What condition is associated with CHAT p.Arg28= (c.84G>A)?

CHAT p.Arg28= (c.84G>A) is associated with congenital myasthenic syndrome 6 (ClinVar).

How common is CHAT p.Arg28= (c.84G>A) in the general population?

CHAT p.Arg28= (c.84G>A) is very rare (popmax 8.72e-05%, nfe) (gnomAD).

CHAT p.Arg28=

c.84G>A · rs745753124 · VCV2911036

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 8.72e-05%, nfe)

Conditions

congenital myasthenic syndrome 6

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 -0.11	GERP -2, phastCons 0.001
Overall
CADD	8.987	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 8.72e-05% European (non-Finnish) · 1/1,146,626 alleles

Overall 7.16e-05% 1/1,396,458 alleles · very rare

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: CHAT
Protein: p.Arg28=
Coding: c.84G>A
MANE Select: NM_020549
dbSNP: rs745753124
Type: single nucleotide variant
Location: chr10:49614273 (GRCh38)
Gene constraint: LOEUF 0.973 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 84.73 · 8 PDB
Residue 28: the 'disordered' region

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

Disease context

congenital myasthenic syndrome 6 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Similar variants

CHAT p.Arg28Ser Uncertain significance ★★ ⚠ same residue
CHAT p.Arg28Gly Uncertain significance ★ ⚠ same residue
CHAT p.Arg28fs Likely pathogenic ★ same residue
CHAT c.1282-2A>T Likely pathogenic ★★ same condition
CHAT c.1840-9A>G Pathogenic/Likely pathogenic ★★ same condition
CHAT c.698+1G>T Likely pathogenic ★★ same condition
CHAT c.698+2T>C Likely pathogenic ★★ same condition
CHAT p.Ala557Thr 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/chat-p-arg28 (accessed [today's date]).

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