Is ALG3 c.605+9C>T pathogenic?

ALG3 c.605+9C>T is classified Likely benign in ALG3 (ClinVar, Single submitter, 1 submitter; last evaluated 2025-06-02). Very rare (popmax 0.000763%, nfe); Associated with ALG3-congenital disorder of glycosylation.

What condition is associated with ALG3 c.605+9C>T?

ALG3 c.605+9C>T is associated with ALG3-congenital disorder of glycosylation (ClinVar).

How common is ALG3 c.605+9C>T in the general population?

ALG3 c.605+9C>T is very rare (popmax 0.000763%, nfe) (gnomAD).

How is ALG3-CDG inherited?

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

ALG3 c.605+9C>T

rs1177025121 · VCV1624305

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.000763%, nfe)

Conditions

ALG3-congenital disorder of glycosylation

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
Splice region	donor +9	near-intronic (+9 nt from the splice site)
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 2.9	GERP 0.3, phastCons 0.99
Non-coding constraint	Z 1.96	1 kb window · o/e 0.86 · regional · uncalibrated
Overall
CADD	15.5	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.000763% European (non-Finnish) · 9/1,179,862 alleles

Filtering AF 0.000359% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00026%

Overall 0.000558% 9/1,613,690 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: ALG3
Coding: c.605+9C>T
MANE Select: NM_005787
dbSNP: rs1177025121
Type: single nucleotide variant
Location: chr3:184245189 (GRCh38)
Gene constraint: LOEUF 0.972 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 89.05

Full ALG3 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

ALG3-congenital disorder of glycosylation — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For ALG3-CDG (Orphanet):

Inheritance: Autosomal recessive
Onset: Infancy, Neonatal

Similar variants

ALG3 c.444+1G>T Likely pathogenic ★★ same condition
ALG3 p.Arg171Gln Pathogenic/Likely pathogenic ★★ same condition
ALG3 p.Arg266Cys Pathogenic ★★ same condition
ALG3 p.Arg354Cys Likely pathogenic ★★ same condition
ALG3 p.Arg354His Pathogenic/Likely pathogenic ★★ same condition
ALG3 p.Asn174Ser Likely pathogenic ★★ ⚠ same condition
ALG3 p.Gly55= Pathogenic/Likely pathogenic ★★ same condition
ALG3 p.Ile69Thr 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/alg3-c-605-plus-9c-t (accessed [today's date]).

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