Is CHRNB2 p.Gln480Ter (c.1438C>T) pathogenic?

CHRNB2 p.Gln480Ter (c.1438C>T) is classified Uncertain significance in CHRNB2 (ClinVar, Multiple submitters, 2 submitters; last evaluated 2025-01-31). Very rare (popmax 0.00223%, eas); Associated with familial sleep-related hypermotor epilepsy.

What condition is associated with CHRNB2 p.Gln480Ter (c.1438C>T)?

CHRNB2 p.Gln480Ter (c.1438C>T) is associated with familial sleep-related hypermotor epilepsy (ClinVar).

How common is CHRNB2 p.Gln480Ter (c.1438C>T) in the general population?

CHRNB2 p.Gln480Ter (c.1438C>T) is very rare (popmax 0.00223%, eas) (gnomAD).

How is Sleep-related hypermotor epilepsy inherited?

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

CHRNB2 p.Gln480Ter

c.1438C>T · rs752248053 · VCV2880003

Uncertain significance Multiple submitters

Classification

Uncertain significance

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 2 submitters

Consequence

nonsense (stop-gain)

predicted LoF

gnomAD v4.1

Rare

very rare (popmax 0.00223%, eas)

Conditions

familial sleep-related hypermotor epilepsy

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	escapes	premature termination codon in the last exon (6 of 6) — the truncated protein is likely expressed. PVS1 input, not an applied code
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 7.6	GERP 2, phastCons 1
Overall
CADD	41.0	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 0.00223% East Asian · 1/44,894 alleles

Filtering AF 0.000124% ClinGen BA1/BS1 input FAF95, joint · FAF99 9e-05%

Overall 0.000372% 6/1,614,042 alleles · very rare

Ancestry group	Frequency	1 in
East Asiangrpmax	0.00223%	44,894
European (non-Finnish)	0.000424%	236,009

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.Gln480Ter
Coding: c.1438C>T
MANE Select: NM_000748
dbSNP: rs752248053
Type: single nucleotide variant
Location: chr1:154575861 (GRCh38)
Gene constraint: LOEUF 1.116 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 81.16 · 15 PDB
Residue 480: a turn

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.Gln480del Uncertain significance ★ 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-gln480ter (accessed [today's date]).

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