Is CTPS1 p.Gly397= (c.1191C>T) pathogenic?

CTPS1 p.Gly397= (c.1191C>T) is classified Benign/Likely benign in CTPS1 (ClinVar, Multiple submitters, 5 submitters; last evaluated 2026-01-07). Rare (popmax 0.255%, afr); Associated with combined immunodeficiency due to CTPS1 deficiency.

What condition is associated with CTPS1 p.Gly397= (c.1191C>T)?

CTPS1 p.Gly397= (c.1191C>T) is associated with combined immunodeficiency due to CTPS1 deficiency (ClinVar).

How common is CTPS1 p.Gly397= (c.1191C>T) in the general population?

CTPS1 p.Gly397= (c.1191C>T) is rare (popmax 0.255%, afr) (gnomAD).

CTPS1 p.Gly397=

Q: How is Severe combined immunodeficiency due to CTPS1 deficiency inherited?

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

c.1191C>T · rs150821317 · VCV541958

Benign/Likely benign Multiple submitters

Classification

Benign/Likely benign

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 5 submitters

gnomAD v4.1

Rare

rare (popmax 0.255%, afr)

Conditions

combined immunodeficiency due to CTPS1 deficiency

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	<0.2	all four deltas below 0.2 · C>G here scores Δ0.47 · evaluated, not missing
Constraint at this position
Conservation	phyloP -1.4	GERP -4.7
Overall
CADD	5.83	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.255% African / African-American · 191/74,902 alleles

Filtering AF 0.225% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.214%

Overall 0.0151% 243/1,613,986 alleles · rare

Ancestry group	Frequency	1 in
African / African-Americangrpmax	0.255%	392
Remaining individualsnot grpmax-eligible	0.0192%	5,207
Middle Eastern	0.0164%	6,084
Admixed American	0.00667%	15,001
Ashkenazi Jewishnot grpmax-eligible	0.00338%	29,604
European (non-Finnish)	0.0028%	35,758
East Asian	0.00223%	44,894

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: CTPS1
Protein: p.Gly397=
Coding: c.1191C>T
MANE Select: NM_001905
dbSNP: rs150821317
Type: single nucleotide variant
Location: chr1:41003115 (GRCh38)
Gene constraint: LOEUF 0.423 · pLI 1.00 (gnomAD)
Structure: AlphaFold pLDDT 91.46 · 7 PDB
Residue 397: the glutamine amidotransferase type-1 domain; a β-strand

Full CTPS1 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

combined immunodeficiency due to CTPS1 deficiency — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Severe combined immunodeficiency due to CTPS1 deficiency (Orphanet):

Inheritance: Autosomal recessive
Onset: Childhood, Infancy, Neonatal

Similar variants

CTPS1 c.1692-1G>C Pathogenic ★★ same condition
CTPS1 c.1095-5T>G Uncertain significance ★★ same condition
CTPS1 p.Ala471Thr Uncertain significance ★★ ⚠ same condition
CTPS1 p.Arg102Trp Uncertain significance ★★ ⚠ same condition
CTPS1 p.Arg294His Uncertain significance ★★ ⚠ same condition
CTPS1 p.Arg376Gln Uncertain significance ★★ ⚠ same condition
CTPS1 p.Arg550Gln Uncertain significance ★★ ⚠ same condition
CTPS1 p.Asn412Ser 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/ctps1-p-gly397 (accessed [today's date]).

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