Is CDKN1C p.Ala266Ser (c.796G>T) pathogenic?

CDKN1C p.Ala266Ser (c.796G>T) is classified Uncertain significance in CDKN1C (ClinVar, Single submitter, 1 submitter; last evaluated 2025-08-07). AlphaMissense: likely benign (0.2597); Very rare (popmax 8.96e-05%, nfe); Associated with Beckwith-Wiedemann syndrome.

What condition is associated with CDKN1C p.Ala266Ser (c.796G>T)?

CDKN1C p.Ala266Ser (c.796G>T) is associated with Beckwith-Wiedemann syndrome (ClinVar).

How common is CDKN1C p.Ala266Ser (c.796G>T) in the general population?

CDKN1C p.Ala266Ser (c.796G>T) is very rare (popmax 8.96e-05%, nfe) (gnomAD).

What do computational predictors say about CDKN1C p.Ala266Ser (c.796G>T)?

AlphaMissense predicts likely benign (score 0.2597) — an in-silico prediction, not a clinical call.

CDKN1C p.Ala266Ser

c.796G>T · rs759474789 · VCV858662

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely benign

0.2597 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 8.96e-05%, nfe)

Missense predictors

0/2 damaging

AlphaMissense, SaProt · REVEL no call

Conditions

Beckwith-Wiedemann syndrome

Computational evidence

Protein change
AlphaMissense	0.2597	likely benign
REVEL	0.407	indeterminate
SaProt	LLR -6.06	tolerated
⇒ AlphaMissense and SaProt both call this tolerated; REVEL makes no call.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 1.3	GERP 0.77, phastCons 1
Overall
CADD	24.4	PHRED · no single calibrated threshold — expert panels disagree

ClinVar classifies this uncertain; the computational predictors unanimously lean tolerated — a triage signal, not a reclassification

AlphaMissense carries the ACMG weight for missense; REVEL and SaProt are independent agreement signals.

⚠ Isoform check: AlphaMissense numbered on a different transcript (AM A277S vs ClinVar A266S) — verify the residue.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 8.96e-05% European (non-Finnish) · 1/1,116,516 alleles

Overall 7.47e-05% 1/1,339,462 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: CDKN1C
Protein: p.Ala266Ser
Coding: c.796G>T
MANE Select: NM_001122630
dbSNP: rs759474789
Type: single nucleotide variant
Location: chr11:2884126 (GRCh38)
Gene constraint: LOEUF 1.943 · pLI <0.01 · ClinGen HI 3/3 (gnomAD)
Structure: AlphaFold pLDDT 63.93

Full CDKN1C gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

Beckwith-Wiedemann syndrome — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Similar variants

CDKN1C p.Ala266Thr Uncertain significance ★★ ⚠ same residue
CDKN1C p.Ala266Val Uncertain significance ★★ ⚠ same residue
CDKN1C p.Ala266Pro Uncertain significance ★ ⚠ same residue
CDKN1C p.Ala266= Likely benign ★ same residue
CDKN1C p.Asp263Asn Pathogenic ★★ ⚠ same condition
CDKN1C p.Cys19Ter Pathogenic/Likely pathogenic ★★ same condition
CDKN1C p.Gln219Ter Pathogenic ★★ same condition
CDKN1C p.Gln221Ter 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/cdkn1c-p-ala266ser (accessed [today's date]).

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