Is ALG9 c.*1420C>G pathogenic?

ALG9 c.1420C>G is classified Uncertain significance in ALG9 (ClinVar, Single submitter, 1 submitter; last evaluated 2018-01-12). Low-frequency (popmax 1.6%, amr); Associated with ALG9-congenital disorder of glycosylation.

What condition is associated with ALG9 c.*1420C>G?

ALG9 c.*1420C>G is associated with ALG9-congenital disorder of glycosylation (ClinVar).

How common is ALG9 c.*1420C>G in the general population?

ALG9 c.*1420C>G is low-frequency (popmax 1.6%, amr) (gnomAD).

How is ALG9-CDG inherited?

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

ALG9 c.*1420C>G

rs143933458 · VCV302409

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

low-frequency (popmax 1.6%, amr)

Conditions

ALG9-congenital disorder of glycosylation

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 4.6	GERP 0.69, phastCons 1
Non-coding constraint	Z 1.99	1 kb window · o/e 0.86 · regional · uncalibrated
Overall
CADD	12.36	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 1.6% Admixed American · 245/15,300 alleles

Filtering AF 1.44% ClinGen BA1/BS1 input FAF95, joint · FAF99 1.37%

Overall 0.175% 266/152,318 alleles · low-frequency

Ancestry group	Frequency	1 in
Admixed Americangrpmax	1.6%	62
East Asian	0.25%	400
African / African-American	0.0144%	6,929
European (non-Finnish)	0.00294%	34,024

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: ALG9
Coding: c.*1420C>G
MANE Select: NM_024740
dbSNP: rs143933458
Type: single nucleotide variant
Location: chr11:111784977 (GRCh38)
Gene constraint: LOEUF 0.853 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 88.35 · 2 PDB

Full ALG9 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

ALG9-congenital disorder of glycosylation — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For ALG9-CDG (Orphanet):

Inheritance: Autosomal recessive
Onset: Antenatal, Infancy, Neonatal

Similar variants

ALG9 c.566-1G>A Pathogenic/Likely pathogenic ★★ same condition
ALG9 c.896-2A>G Likely pathogenic ★★ same condition
ALG9 p.Arg143Ter Pathogenic/Likely pathogenic ★★ same condition
ALG9 p.Trp248Ter Pathogenic/Likely pathogenic ★★ same condition
ALG9 p.Tyr287Cys Pathogenic/Likely pathogenic ★★ same condition
ALG9 c.*1607C>T Uncertain significance ★★ same condition
ALG9 c.*1624A>C Uncertain significance ★★ same condition
ALG9 c.*1722C>T 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/alg9-c-star-1420c-g (accessed [today's date]).

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