Is CPS1 p.Ala334Thr (c.1000G>A) pathogenic?

CPS1 p.Ala334Thr (c.1000G>A) is classified Uncertain significance in CPS1 (ClinVar, Single submitter, 1 submitter; last evaluated 2023-06-29). AlphaMissense: likely benign (0.1984); Absent from gnomAD v4.1; Associated with carbamoyl phosphate synthetase I deficiency disease.

What condition is associated with CPS1 p.Ala334Thr (c.1000G>A)?

CPS1 p.Ala334Thr (c.1000G>A) is associated with carbamoyl phosphate synthetase I deficiency disease (ClinVar).

How common is CPS1 p.Ala334Thr (c.1000G>A) in the general population?

CPS1 p.Ala334Thr (c.1000G>A) is absent from gnomAD v4.1 (gnomAD).

How is Carbamoyl-phosphate synthetase 1 deficiency inherited?

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

What do computational predictors say about CPS1 p.Ala334Thr (c.1000G>A)?

AlphaMissense predicts likely benign (score 0.1984) — an in-silico prediction, not a clinical call.

CPS1 p.Ala334Thr

c.1000G>A · rs2106111068 · VCV1364241

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely benign

0.1984 · ACMG-weighted

gnomAD v4.1

Absent

absent from gnomAD v4.1

Missense predictors

0/2 damaging

AlphaMissense, SaProt · REVEL no call

Conditions

carbamoyl phosphate synthetase I deficiency disease

Computational evidence

Protein change
AlphaMissense	0.1984	likely benign
REVEL	0.428	indeterminate
SaProt	LLR -7.92	tolerated
⇒ AlphaMissense and SaProt both call this tolerated; REVEL makes no call.
Splicing
SpliceAI	<0.2	all four deltas below 0.2 · G>T here scores Δ0.43 · evaluated, not missing
Constraint at this position
Conservation	phyloP 6.6	GERP 1, phastCons 1
Regional constraint	o/e 0.93	unconstrained · MANE · 121 kb · p 0.0019 · regional, not allelic
Overall
CADD	19.33	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.

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: CPS1
Protein: p.Ala334Thr
Coding: c.1000G>A
MANE Select: NM_001875
dbSNP: rs2106111068
Type: single nucleotide variant
Location: chr2:210591883 (GRCh38)
Gene constraint: LOEUF 0.764 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 93.80 · 14 PDB
Residue 334: the glutamine amidotransferase type-1 domain; a β-strand

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.Ala334Pro Likely pathogenic ★ ⚠ 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
CPS1 c.1837-8A>G 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-ala334thr (accessed [today's date]).

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