Is PYGL p.Thr552= (c.1656G>A) pathogenic?

PYGL p.Thr552= (c.1656G>A) is classified Likely benign in PYGL (ClinVar, Single submitter, 1 submitter; last evaluated 2024-02-17). Ultra-rare (popmax 0.0586%, afr); Associated with glycogen storage disease VI.

What condition is associated with PYGL p.Thr552= (c.1656G>A)?

PYGL p.Thr552= (c.1656G>A) is associated with glycogen storage disease VI (ClinVar).

How common is PYGL p.Thr552= (c.1656G>A) in the general population?

PYGL p.Thr552= (c.1656G>A) is ultra-rare (popmax 0.0586%, afr) (gnomAD).

PYGL p.Thr552=

Q: How is Glycogen storage disease due to liver glycogen phosphorylase deficiency inherited?

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

c.1656G>A · rs376165151 · VCV755359

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

ultra-rare (popmax 0.0586%, afr)

Conditions

glycogen storage disease VI

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 0.26	GERP 0.055, phastCons 0.98
Overall
CADD	13.84	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.0586% African / African-American · 44/75,048 alleles

Filtering AF 0.0448% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.04%

Overall 0.00415% 67/1,614,108 alleles · ultra-rare exomes 37/1,461,774 · genomes 30/152,334 · joint denominator

Ancestry group	Frequency	1 in
African / African-Americangrpmax	0.0586%	1,706
Middle Eastern	0.0495%	2,021
South Asian	0.00659%	15,180
Remaining individualsnot grpmax-eligible	0.0048%	20,835
Ashkenazi Jewishnot grpmax-eligible	0.00338%	29,606
Admixed American	0.00333%	30,012
East Asian	0.00223%	44,874
European (non-Finnish)	0.000593%	168,564

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: PYGL
Protein: p.Thr552=
Coding: c.1656G>A
MANE Select: NM_002863
dbSNP: rs376165151
Type: single nucleotide variant
Location: chr14:50912268 (GRCh38)
Gene constraint: LOEUF 1.048 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 92.87 · 19 PDB
Residue 552: an α-helix

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

Disease context

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

For Glycogen storage disease due to liver glycogen phosphorylase deficiency (Orphanet):

Inheritance: Autosomal recessive
Onset: Childhood

Similar variants

PYGL c.1404-1G>A Pathogenic/Likely pathogenic ★★ same condition
PYGL c.1620+1G>A Pathogenic/Likely pathogenic ★★ same condition
PYGL c.1620+1G>C Pathogenic ★★ same condition
PYGL c.1768+1G>A Pathogenic ★★ same condition
PYGL c.772+1G>A Pathogenic/Likely pathogenic ★★ same condition
PYGL p.Arg576Ter Pathogenic ★★ same condition
PYGL p.Arg94Ter Pathogenic ★★ same condition
PYGL p.Gln577Ter 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/pygl-p-thr552 (accessed [today's date]).

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