Is APC p.Cys447Ser (c.1340G>C) pathogenic?

APC p.Cys447Ser (c.1340G>C) is classified Uncertain significance in APC (ClinVar, Single submitter, 1 submitter; last evaluated 2022-12-19). AlphaMissense: likely pathogenic (0.8224); Absent from gnomAD v4.1; Associated with familial adenomatous polyposis 1.

What condition is associated with APC p.Cys447Ser (c.1340G>C)?

APC p.Cys447Ser (c.1340G>C) is associated with familial adenomatous polyposis 1 (ClinVar).

How common is APC p.Cys447Ser (c.1340G>C) in the general population?

APC p.Cys447Ser (c.1340G>C) is absent from gnomAD v4.1 (gnomAD).

How is Familial adenomatous polyposis inherited?

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

What do computational predictors say about APC p.Cys447Ser (c.1340G>C)?

AlphaMissense predicts likely pathogenic (score 0.8224) — an in-silico prediction, not a clinical call.

APC p.Cys447Ser

c.1340G>C · rs2149792069 · VCV2822243

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely pathogenic

0.8224 · ACMG-weighted

gnomAD v4.1

Absent

absent from gnomAD v4.1

Conditions

familial adenomatous polyposis 1

Computational evidence

Protein change
AlphaMissense	0.8224	likely pathogenic
REVEL	0.455	indeterminate
SaProt	—	not scored · why
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 12	GERP 2.9, phastCons 1
Regional constraint	o/e 0.94	unconstrained · MANE · 8,173 bp · p 0.36 · regional, not allelic
Overall
CADD	27.4	PHRED · no single calibrated threshold — expert panels disagree

AlphaMissense carries the ACMG weight for missense; REVEL is an independent agreement signal.

Population frequency

gnomAD v4.1 · exomes + genomes

Absent from gnomAD v4.1. Not observed in any sequenced alleles — a rarity signal (ACMG PM2-supporting), not evidence of pathogenicity on its own.

Variant & gene context

Gene: APC
Protein: p.Cys447Ser
Coding: c.1340G>C
MANE Select: NM_000038
dbSNP: rs2149792069
Type: single nucleotide variant
Location: chr5:112821923 (GRCh38)
Gene constraint: LOEUF 0.321 · pLI 1.00 · ClinGen HI 3/3 (gnomAD)
Residue 447: an α-helix

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

Disease context

familial adenomatous polyposis 1 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Familial adenomatous polyposis (Orphanet):

Inheritance: Autosomal dominant, Autosomal recessive
Onset: Adult
Prevalence: 1-9 / 100 000 (Worldwide)

Similar variants

APC p.Cys447Ter Pathogenic/Likely pathogenic ★★ same residue
APC p.Cys447= Likely benign ★ same residue
APC c.1312+3A>C Likely pathogenic ★★★ same condition
APC c.1312+3A>G Pathogenic ★★★ same condition
APC c.1312+5G>A Likely pathogenic ★★★ same condition
APC c.1312+5G>C Likely pathogenic ★★★ same condition
APC c.1409-3T>G Likely pathogenic ★★★ same condition
APC c.1409-5A>G 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/apc-p-cys447ser (accessed [today's date]).

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