Is CTSA c.306+2T>A pathogenic?

CTSA c.306+2T>A is classified Likely pathogenic in CTSA (ClinVar, Single submitter, 1 submitter; last evaluated 2023-09-26). Very rare (popmax 0.0022%, sas); Associated with galactosialidosis.

What condition is associated with CTSA c.306+2T>A?

CTSA c.306+2T>A is associated with galactosialidosis (ClinVar).

How common is CTSA c.306+2T>A in the general population?

CTSA c.306+2T>A is very rare (popmax 0.0022%, sas) (gnomAD).

How is Galactosialidosis inherited?

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

CTSA c.306+2T>A

rs2515433373 · VCV2838177

Likely pathogenic Single submitter

Classification

Likely pathogenic

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

Consequence

canonical splice-site (±1/±2)

predicted LoF

gnomAD v4.1

Rare

very rare (popmax 0.0022%, sas)

Conditions

galactosialidosis

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation/SpliceAI carries the signal.
Consequence	canonical splice-site (±1/±2)	predicted loss-of-function
Splicing
Splice region	donor +2	canonical splice dinucleotide (donor +2) · inside the BP7-excluded zone
SpliceAI	Δ0.99	donor loss · deltas
Pangolin	Δ0.88	loss · gain 0.19 · agrees with SpliceAI · independent
Constraint at this position
Conservation	phyloP 7.9	GERP 2, phastCons 1
Non-coding constraint	Z 3.21	1 kb window · o/e 0.78 · regional · uncalibrated
Overall
CADD	34.0	PHRED · no single calibrated threshold — expert panels disagree

Predicted loss-of-function is descriptive, not an applied PVS1 code.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.0022% South Asian · 2/91,020 alleles

Filtering AF 0.000365% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000137%

Overall 0.000137% 2/1,459,398 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: CTSA
Coding: c.306+2T>A
MANE Select: NM_000308
dbSNP: rs2515433373
Type: single nucleotide variant
Location: chr20:45892029 (GRCh38)
Gene constraint: LOEUF 0.851 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 94.59 · 12 PDB

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 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
CTSA p.Cys281Ter 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-c-306-plus-2t-a (accessed [today's date]).

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