Is C1S p.Pro291= (c.873A>G) pathogenic?

C1S p.Pro291= (c.873A>G) is classified Likely benign in C1S (ClinVar, Single submitter, 1 submitter; last evaluated 2026-01-25). Very rare (popmax 8.63e-05%, nfe).

How common is C1S p.Pro291= (c.873A>G) in the general population?

C1S p.Pro291= (c.873A>G) is very rare (popmax 8.63e-05%, nfe) (gnomAD).

C1S p.Pro291=

c.873A>G · VCV3654670

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 8.63e-05%, nfe)

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 1.8	GERP -2, phastCons 1
Overall
CADD	13.0	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 8.63e-05% European (non-Finnish) · 1/1,158,214 alleles

Overall 0.000657% 1/152,228 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: C1S
Protein: p.Pro291=
Coding: c.873A>G
MANE Select: NM_001734
Type: single nucleotide variant
Location: chr12:7066519 (GRCh38)
Gene constraint: LOEUF 0.783 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 88.02 · 14 PDB
Residue 291: a β-strand

Full C1S gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Similar variants

C1S p.Pro291Ser Uncertain significance ★ ⚠ same residue
C1S p.Arg523Ter Pathogenic ★★ same type
C1S c.1196-3C>T Uncertain significance ★★ same type
C1S c.717+5G>A Uncertain significance ★★ same type
C1S c.717+6T>A Uncertain significance ★★ same type
C1S p.Ala227Val Uncertain significance ★★ ⚠ same type
C1S p.Ala231Val Uncertain significance ★★ ⚠ same type
C1S p.Ala584Val Uncertain significance ★★ ⚠ same type

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/c1s-p-pro291 (accessed [today's date]).

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