Is CHRNB2 p.Thr225Arg (c.674C>G) pathogenic?

CHRNB2 p.Thr225Arg (c.674C>G) is classified Uncertain significance in CHRNB2 (ClinVar, Multiple submitters, 2 submitters; last evaluated 2023-11-19). AlphaMissense: likely pathogenic (0.8435); Very rare (popmax 0.00167%, amr); Associated with familial sleep-related hypermotor epilepsy.

What condition is associated with CHRNB2 p.Thr225Arg (c.674C>G)?

CHRNB2 p.Thr225Arg (c.674C>G) is associated with familial sleep-related hypermotor epilepsy (ClinVar).

How common is CHRNB2 p.Thr225Arg (c.674C>G) in the general population?

CHRNB2 p.Thr225Arg (c.674C>G) is very rare (popmax 0.00167%, amr) (gnomAD).

How is Sleep-related hypermotor epilepsy inherited?

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

What do computational predictors say about CHRNB2 p.Thr225Arg (c.674C>G)?

AlphaMissense predicts likely pathogenic (score 0.8435) — an in-silico prediction, not a clinical call.

CHRNB2 p.Thr225Arg

c.674C>G · rs201952018 · VCV1690537

Uncertain significance Multiple submitters

Classification

Uncertain significance

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 2 submitters

AlphaMissense

likely pathogenic

0.8435 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.00167%, amr)

Missense predictors

3/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

familial sleep-related hypermotor epilepsy

Computational evidence

Protein change
AlphaMissense	0.8435	likely pathogenic
REVEL	0.888	moderately pathogenic-leaning
SaProt	LLR -14.08	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, phastCons 1
Regional constraint	o/e 0.74	unconstrained · MANE · 3,773 bp · p 1.9e-08 · regional, not allelic
Overall
CADD	26.7	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

Grpmax group 0.00167% Admixed American · 1/60,030 alleles

Overall 6.84e-05% 1/1,461,706 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: CHRNB2
Protein: p.Thr225Arg
Coding: c.674C>G
MANE Select: NM_000748
dbSNP: rs201952018
Type: single nucleotide variant
Location: chr1:154571497 (GRCh38)
Gene constraint: LOEUF 1.116 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 81.16 · 15 PDB
Residue 225: a β-strand

Full CHRNB2 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

familial sleep-related hypermotor epilepsy — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Sleep-related hypermotor epilepsy (Orphanet):

Inheritance: Autosomal dominant
Onset: Adolescent, Adult, Childhood

Similar variants

CHRNB2 p.Thr225= Likely benign ★ same residue
CHRNB2 p.Val287Leu Pathogenic/Likely pathogenic ★★ same condition
CHRNB2 p.Val287Met Pathogenic ★★ same condition
CHRNB2 p.Val308Ala Pathogenic/Likely pathogenic ★★ same condition
CHRNB2 c.1338+3G>T Uncertain significance ★★ same condition
CHRNB2 c.366-3C>T Uncertain significance ★★ same condition
CHRNB2 p.Ala135Val Uncertain significance ★★ ⚠ same condition
CHRNB2 p.Ala154Thr 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/chrnb2-p-thr225arg (accessed [today's date]).

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