Is ALG8 p.Arg268Leu (c.803G>T) pathogenic?

ALG8 p.Arg268Leu (c.803G>T) is classified Uncertain significance in ALG8 (ClinVar, Single submitter, 1 submitter; last evaluated 2025-08-24). AlphaMissense: likely pathogenic (0.802); Very rare (popmax 0.00549%, sas); Associated with ALG8-congenital disorder of glycosylation.

What condition is associated with ALG8 p.Arg268Leu (c.803G>T)?

ALG8 p.Arg268Leu (c.803G>T) is associated with ALG8-congenital disorder of glycosylation (ClinVar).

How common is ALG8 p.Arg268Leu (c.803G>T) in the general population?

ALG8 p.Arg268Leu (c.803G>T) is very rare (popmax 0.00549%, sas) (gnomAD).

How is ALG8-CDG inherited?

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

What do computational predictors say about ALG8 p.Arg268Leu (c.803G>T)?

AlphaMissense predicts likely pathogenic (score 0.802) — an in-silico prediction, not a clinical call.

ALG8 p.Arg268Leu

c.803G>T · VCV4777377

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely pathogenic

0.802 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.00549%, sas)

Missense predictors

3/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

ALG8-congenital disorder of glycosylation

Computational evidence

Protein change
AlphaMissense	0.802	likely pathogenic
REVEL	0.95	strongly pathogenic-leaning
SaProt	LLR -13.90	damaging
⇒ AlphaMissense, REVEL and SaProt all call this damaging.
Splicing
SpliceAI	Δ0.28	acceptor loss · deltas
Pangolin	Δ0.25	loss · gain 0.01 · agrees with SpliceAI · independent
Constraint at this position
Conservation	phyloP 4.8	GERP 2.2, phastCons 1
Regional constraint	o/e 0.94	unconstrained · MANE · 39 kb · p 0.14 · regional, not allelic
Overall
CADD	26.4	PHRED · no single calibrated threshold — expert panels disagree

ClinVar classifies this uncertain; the computational predictors unanimously lean damaging — a triage signal, not a reclassification

AlphaMissense carries the ACMG weight for missense; REVEL and SaProt are independent agreement signals.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00549% South Asian · 5/91,026 alleles

Filtering AF 0.00211% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00136%

Overall 0.000411% 6/1,461,538 alleles · very rare

Ancestry group	Frequency	1 in
South Asiangrpmax	0.00549%	18,205
European (non-Finnish)	8.48e-05%	1,179,807

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: ALG8
Protein: p.Arg268Leu
Coding: c.803G>T
MANE Select: NM_024079
Type: single nucleotide variant
Location: chr11:78112745 (GRCh38)
Gene constraint: LOEUF 0.909 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 92.07
Residue 268: a UniProt-annotated variant site (in pcld3)

Full ALG8 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

ALG8-congenital disorder of glycosylation — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For ALG8-CDG (Orphanet):

Inheritance: Autosomal recessive
Onset: Antenatal, Infancy, Neonatal

Similar variants

ALG8 p.Arg268Ter Pathogenic/Likely pathogenic ★★ same residue
ALG8 p.Arg268Gln Benign/Likely benign ★★ ⚠ same residue
ALG8 p.Arg268fs Pathogenic/Likely pathogenic ★★ same residue
ALG8 c.368+2T>G Likely pathogenic ★★ same condition
ALG8 c.674-2A>G Likely pathogenic ★★ same condition
ALG8 c.777+1G>A Likely pathogenic ★★ same condition
ALG8 c.95+1G>A Likely pathogenic ★★ same condition
ALG8 p.Arg179Ter 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/alg8-p-arg268leu (accessed [today's date]).

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