Is CPS1 p.Pro99= (c.297T>G) pathogenic?

CPS1 p.Pro99= (c.297T>G) is classified Likely benign in CPS1 (ClinVar, Single submitter, 1 submitter; last evaluated 2022-12-24). Very rare (popmax 8.48e-05%, nfe); Associated with carbamoyl phosphate synthetase I deficiency disease.

What condition is associated with CPS1 p.Pro99= (c.297T>G)?

CPS1 p.Pro99= (c.297T>G) is associated with carbamoyl phosphate synthetase I deficiency disease (ClinVar).

How common is CPS1 p.Pro99= (c.297T>G) in the general population?

CPS1 p.Pro99= (c.297T>G) is very rare (popmax 8.48e-05%, nfe) (gnomAD).

How is Carbamoyl-phosphate synthetase 1 deficiency inherited?

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

CPS1 p.Pro99=

c.297T>G · rs1246973809 · VCV2823766

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 8.48e-05%, nfe)

Conditions

carbamoyl phosphate synthetase I deficiency disease

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 -2	GERP -5
Overall
CADD	6.594	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 8.48e-05% European (non-Finnish) · 1/1,179,766 alleles

Overall 0.000657% 1/152,122 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: CPS1
Protein: p.Pro99=
Coding: c.297T>G
MANE Select: NM_001875
dbSNP: rs1246973809
Type: single nucleotide variant
Location: chr2:210576406 (GRCh38)
Gene constraint: LOEUF 0.764 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 93.80 · 14 PDB
Residue 99: a β-strand; the 'anthranilate phosphoribosyltransferase homolog' region

Full CPS1 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

carbamoyl phosphate synthetase I deficiency disease — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Carbamoyl-phosphate synthetase 1 deficiency (Orphanet):

Inheritance: Autosomal recessive
Onset: All ages

Similar variants

CPS1 p.Pro99Thr Uncertain significance ★★ ⚠ same residue
CPS1 p.Pro99Leu Conflicting classifications of pathogenicity ★ ⚠ same residue
CPS1 c.1086+1G>A Likely pathogenic ★★ same condition
CPS1 c.1087-1G>T Pathogenic/Likely pathogenic ★★ same condition
CPS1 c.1165-2A>G Likely pathogenic ★★ same condition
CPS1 c.1263+5G>C Pathogenic/Likely pathogenic ★★ same condition
CPS1 c.1549+1G>A Pathogenic/Likely pathogenic ★★ same condition
CPS1 c.1549+1G>T Pathogenic/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/cps1-p-pro99 (accessed [today's date]).

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