Is AGL p.Arg8Ter (c.22C>T) pathogenic?

AGL p.Arg8Ter (c.22C>T) is classified Pathogenic/Likely pathogenic in AGL (ClinVar, Multiple submitters, 6 submitters; last evaluated 2026-01-12). Very rare (popmax 0.000339%, nfe); Associated with glycogen storage disease III.

What condition is associated with AGL p.Arg8Ter (c.22C>T)?

AGL p.Arg8Ter (c.22C>T) is associated with glycogen storage disease III (ClinVar).

How common is AGL p.Arg8Ter (c.22C>T) in the general population?

AGL p.Arg8Ter (c.22C>T) is very rare (popmax 0.000339%, nfe) (gnomAD).

AGL p.Arg8Ter

Q: How is Glycogen storage disease due to glycogen debranching enzyme deficiency inherited?

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

c.22C>T · rs1057516870 · VCV370924

Pathogenic/Likely pathogenic Multiple submitters

Classification

Pathogenic/Likely pathogenic

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 6 submitters

Consequence

nonsense (stop-gain)

predicted LoF

gnomAD v4.1

Rare

very rare (popmax 0.000339%, nfe)

Conditions

glycogen storage disease III

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Consequence	nonsense (stop-gain)	predicted loss-of-function
NMD	predicted	premature termination codon in exon 2 of 34
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 1.8	GERP -3.2, phastCons 1
Overall
CADD	36.0	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 0.000339% European (non-Finnish) · 4/1,179,916 alleles

Filtering AF 7.9e-05% ClinGen BA1/BS1 input FAF95, joint · FAF99 5.4e-05%

Overall 0.000248% 4/1,613,882 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: AGL
Protein: p.Arg8Ter
Coding: c.22C>T
MANE Select: NM_000642
dbSNP: rs1057516870
Type: single nucleotide variant
Location: chr1:99851064 (GRCh38)
Gene constraint: LOEUF 0.72 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 92.88 · 1 PDB
Residue 8: the 'amylo-1,6-glucosidase' region; a β-strand

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

Disease context

glycogen storage disease III — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Glycogen storage disease due to glycogen debranching enzyme deficiency (Orphanet):

Inheritance: Autosomal recessive
Onset: Childhood, Infancy
Prevalence: 1-9 / 100 000 (United States)

Similar variants

AGL p.Arg8Gly Uncertain significance ⚠ same residue
AGL p.Arg8fs Pathogenic/Likely pathogenic ★★ same residue
AGL c.1283+2T>C Likely pathogenic ★★ same condition
AGL c.1284-1G>A Likely pathogenic ★★ same condition
AGL c.1284-2A>G Likely pathogenic ★★ same condition
AGL c.1423+1G>A Pathogenic ★★ same condition
AGL c.1423+1G>C Pathogenic ★★ same condition
AGL c.1423+1G>T 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/agl-p-arg8ter (accessed [today's date]).

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