Is ALG3 p.Leu418= (c.1254G>A) pathogenic?

ALG3 p.Leu418= (c.1254G>A) is classified Likely benign in ALG3 (ClinVar, Single submitter, 1 submitter; last evaluated 2024-02-23). Ultra-rare (popmax 0.0166%, mid); Associated with ALG3-congenital disorder of glycosylation.

What condition is associated with ALG3 p.Leu418= (c.1254G>A)?

ALG3 p.Leu418= (c.1254G>A) is associated with ALG3-congenital disorder of glycosylation (ClinVar).

How common is ALG3 p.Leu418= (c.1254G>A) in the general population?

ALG3 p.Leu418= (c.1254G>A) is ultra-rare (popmax 0.0166%, mid) (gnomAD).

How is ALG3-CDG inherited?

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

ALG3 p.Leu418=

c.1254G>A · rs925568475 · VCV2151586

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

ultra-rare (popmax 0.0166%, mid)

Conditions

ALG3-congenital disorder of glycosylation

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
REVEL	0.111	moderately benign-leaning
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 0.83	GERP 0.67, phastCons 1
Overall
CADD	7.609	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.0166% Middle Eastern · 1/6,036 alleles

Filtering AF 0.00817% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00634%

Overall 0.00137% 22/1,607,158 alleles · ultra-rare

Ancestry group	Frequency	1 in
Middle Easterngrpmax	0.0166%	6,036
African / African-American	0.0147%	6,799
Remaining individualsnot grpmax-eligible	0.00643%	15,543
Admixed American	0.00167%	59,794
European (non-Finnish)	0.000426%	235,004

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: ALG3
Protein: p.Leu418=
Coding: c.1254G>A
MANE Select: NM_005787
dbSNP: rs925568475
Type: single nucleotide variant
Location: chr3:184242577 (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-p-leu418 (accessed [today's date]).

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