Is C3 p.Cys694Phe (c.2081G>T) pathogenic?

C3 p.Cys694Phe (c.2081G>T) is classified Uncertain significance in C3 (ClinVar, Single submitter, 1 submitter; last evaluated 2025-09-30). AlphaMissense: likely pathogenic (0.9891); Absent from gnomAD v4.1; Associated with C3 glomerulonephritis.

What condition is associated with C3 p.Cys694Phe (c.2081G>T)?

C3 p.Cys694Phe (c.2081G>T) is associated with C3 glomerulonephritis (ClinVar).

How common is C3 p.Cys694Phe (c.2081G>T) in the general population?

C3 p.Cys694Phe (c.2081G>T) is absent from gnomAD v4.1 (gnomAD).

What do computational predictors say about C3 p.Cys694Phe (c.2081G>T)?

AlphaMissense predicts likely pathogenic (score 0.9891) — an in-silico prediction, not a clinical call.

C3 p.Cys694Phe

c.2081G>T · VCV4280151

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely pathogenic

0.9891 · ACMG-weighted

gnomAD v4.1

Absent

absent from gnomAD v4.1

Missense predictors

2/2 damaging

AlphaMissense, SaProt · REVEL indeterminate

Conditions

C3 glomerulonephritis

Computational evidence

Protein change
AlphaMissense	0.9891	likely pathogenic · top 2% in C3
REVEL	0.602	indeterminate
SaProt	LLR -17.20	damaging
⇒ AlphaMissense and SaProt both call this damaging; REVEL is indeterminate.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 7.4	GERP 1.7, phastCons 1
Regional constraint	o/e 0.74	unconstrained · MANE · 35 kb · p 3.5e-28 · regional, not allelic
Overall
CADD	23.4	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

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: C3
Protein: p.Cys694Phe
Coding: c.2081G>T
MANE Select: NM_000064
Type: single nucleotide variant
Location: chr19:6707240 (GRCh38)
Gene constraint: LOEUF 0.541 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 79.84 · 80 PDB
Residue 694: the anaphylatoxin-like domain; an α-helix; a disulfide bond

Full C3 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

C3 glomerulonephritis — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Similar variants

C3 p.Cys694= Likely benign ★ same residue
C3 p.Arg161Trp Pathogenic/Likely pathogenic ★★ ⚠ same condition
C3 p.Arg592Gln Pathogenic/Likely pathogenic ★★ ⚠ same condition
C3 p.Arg592Trp Likely pathogenic ★★ ⚠ same condition
C3 p.Ala257Thr Uncertain significance ★★ ⚠ same condition
C3 p.Arg1042Gln Uncertain significance ★★ ⚠ same condition
C3 p.Arg1072Trp Uncertain significance ★★ ⚠ same condition
C3 p.Arg1219Cys 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/c3-p-cys694phe (accessed [today's date]).

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