Is CTSA p.Pro165= (c.495G>A) pathogenic?

CTSA p.Pro165= (c.495G>A) is classified Likely benign in CTSA (ClinVar, Single submitter, 1 submitter; last evaluated 2025-11-11). Very rare (popmax 0.005%, amr); Associated with galactosialidosis.

What condition is associated with CTSA p.Pro165= (c.495G>A)?

CTSA p.Pro165= (c.495G>A) is associated with galactosialidosis (ClinVar).

How common is CTSA p.Pro165= (c.495G>A) in the general population?

CTSA p.Pro165= (c.495G>A) is very rare (popmax 0.005%, amr) (gnomAD).

How is Galactosialidosis inherited?

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

CTSA p.Pro165=

c.495G>A · rs1350708938 · VCV1661296

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.005%, amr)

Conditions

galactosialidosis

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation/SpliceAI carries the signal.
Splicing
SpliceAI	Δ0.67	acceptor gain · deltas
Pangolin	Δ0.23	gain · loss 0.02 · agrees with SpliceAI · independent
Constraint at this position
Conservation	phyloP -3.9	GERP -3.3
Overall
CADD	21.6	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.005% Admixed American · 3/60,008 alleles

Filtering AF 0.00133% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000668%

Overall 0.00124% 20/1,614,108 alleles · very rare

Ancestry group	Frequency	1 in
Admixed Americangrpmax	0.005%	20,003
African / African-American	0.004%	24,999
East Asian	0.00223%	44,878
South Asian	0.0022%	45,542
Remaining individualsnot grpmax-eligible	0.0016%	62,510
European (non-Finnish)	0.000847%	118,004

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: CTSA
Protein: p.Pro165=
Coding: c.495G>A
MANE Select: NM_000308
dbSNP: rs1350708938
Type: single nucleotide variant
Location: chr20:45892775 (GRCh38)
Gene constraint: LOEUF 0.851 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 94.59 · 12 PDB
Residue 165: an α-helix; a disulfide bond

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

Disease context

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

For Galactosialidosis (Orphanet):

Inheritance: Autosomal recessive
Onset: All ages

Similar variants

CTSA p.Pro165Leu Uncertain significance ★ ⚠ same residue
CTSA c.1-2A>G Pathogenic/Likely pathogenic ★★ same condition
CTSA c.358-2A>G Likely pathogenic ★★ same condition
CTSA c.601-2A>G Pathogenic/Likely pathogenic ★★ same condition
CTSA c.692+3A>G Pathogenic ★★ same condition
CTSA c.948+1G>A Likely pathogenic ★★ same condition
CTSA p.Arg375Ter Pathogenic/Likely pathogenic ★★ same condition
CTSA p.Cys256Ter 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/ctsa-p-pro165 (accessed [today's date]).

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