Is CHAT p.Cys82Ter (c.246C>A) pathogenic?

CHAT p.Cys82Ter (c.246C>A) is classified Uncertain significance in CHAT (ClinVar, Single submitter, 1 submitter; last evaluated 2021-08-26). Very rare (popmax 0.000174%, nfe); Associated with congenital myasthenic syndrome 6.

What condition is associated with CHAT p.Cys82Ter (c.246C>A)?

CHAT p.Cys82Ter (c.246C>A) is associated with congenital myasthenic syndrome 6 (ClinVar).

How common is CHAT p.Cys82Ter (c.246C>A) in the general population?

CHAT p.Cys82Ter (c.246C>A) is very rare (popmax 0.000174%, nfe) (gnomAD).

CHAT p.Cys82Ter

c.246C>A · rs1409154681 · VCV1376673

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

Consequence

nonsense (stop-gain)

predicted LoF

gnomAD v4.1

Rare

very rare (popmax 0.000174%, nfe)

Conditions

congenital myasthenic syndrome 6

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Consequence	nonsense (stop-gain)	predicted loss-of-function
NMD	predicted	premature termination codon in exon 1 of 15
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 0.66	GERP -1.4, phastCons 0.008
Overall
CADD	31.0	PHRED · no single calibrated threshold — expert panels disagree

Predicted loss-of-function is descriptive, not an applied PVS1 code.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.000174% European (non-Finnish) · 2/1,146,830 alleles

Filtering AF 2.9e-05% ClinGen BA1/BS1 input FAF95, joint · FAF99 1.1e-05%

Overall 0.000143% 2/1,395,438 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.Cys82Ter
Coding: c.246C>A
MANE Select: NM_020549
dbSNP: rs1409154681
Type: single nucleotide variant
Location: chr10:49614435 (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 82: 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.Cys82Gly Uncertain significance ★ ⚠ same residue
SLC18A3 p.Leu82= Likely benign ★ 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
CHAT p.Arg151Ter 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-cys82ter (accessed [today's date]).

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