Is CHRNB2 p.Leu376= (c.1128C>T) pathogenic?

CHRNB2 p.Leu376= (c.1128C>T) is classified Benign/Likely benign in CHRNB2 (ClinVar, Multiple submitters, 5 submitters; last evaluated 2025-12-13). Ultra-rare (popmax 0.048%, amr); Associated with familial sleep-related hypermotor epilepsy.

What condition is associated with CHRNB2 p.Leu376= (c.1128C>T)?

CHRNB2 p.Leu376= (c.1128C>T) is associated with familial sleep-related hypermotor epilepsy (ClinVar).

How common is CHRNB2 p.Leu376= (c.1128C>T) in the general population?

CHRNB2 p.Leu376= (c.1128C>T) is ultra-rare (popmax 0.048%, amr) (gnomAD).

How is Sleep-related hypermotor epilepsy inherited?

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

CHRNB2 p.Leu376=

c.1128C>T · rs113116986 · VCV377681

Benign/Likely benign Multiple submitters

Classification

Benign/Likely benign

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 5 submitters

gnomAD v4.1

Rare

ultra-rare (popmax 0.048%, amr)

Conditions

familial sleep-related hypermotor epilepsy

Computational evidence

Protein change
Missense predictors do not apply to this variant type.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Overall
CADD	0.582	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.048% Admixed American · 25/52,038 alleles

Filtering AF 0.0333% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.0285%

Overall 0.0211% 326/1,546,120 alleles · ultra-rare

Ancestry group	Frequency	1 in
Admixed Americangrpmax	0.048%	2,082
European (non-Finnish)	0.0255%	3,928
Remaining individualsnot grpmax-eligible	0.00664%	15,066
African / African-American	0.00409%	24,468
East Asian	0.00242%	41,298

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.Leu376=
Coding: c.1128C>T
MANE Select: NM_000748
dbSNP: rs113116986
Type: single nucleotide variant
Location: chr1:154571951 (GRCh38)
Gene constraint: LOEUF 1.116 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 81.16 · 15 PDB

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.Leu376Val Uncertain significance ★★ ⚠ same residue
CHRNB2 p.Leu376Phe Conflicting classifications of pathogenicity ★ ⚠ 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

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-leu376 (accessed [today's date]).

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