IEMbase 0497: GYS2-related hepatic glycogen synthase deficiency
Scope
| Field | Value |
|---|---|
| IEMbase ID | 497 |
| Nosology | 3.4.03.01 |
| Gene | GYS2 |
| External IDs | OMIM:240600; ORPHA:2089 |
| Generated mapping | CANDIDATE; MEDIUM; Glycogen_Storage_Disease_Type_I.yaml |
| Candidate DisMech targets | Glycogen_Storage_Disease_Type_I.yaml |
| Review date | 2026-07-07 |
IEMbase phenotype signal
IEMbase represents autosomal recessive GYS2-related hepatic glycogen synthase deficiency as glycogen storage disease type 0a. Treatments are fasting avoidance and a protein-rich diet. Biochemical rows include decreased liver glycogen synthase, increased fasted plasma and urine ketones, decreased-to-normal liver glycogen, decreased fasting glucose, normal-to-increased fed glucose, and increased fed lactate. Clinical rows include absent hepatomegaly, fasting hypoglycemia, and seizures.
DisMech phenotype coverage
Glycogen_Storage_Disease_Type_I.yaml is not the correct target. It models GSD
I due to G6PC1/SLC37A4 defects, with hepatic glycogen accumulation,
hepatomegaly, lactic acidosis, hyperlipidemia, and hyperuricemia. It does not
model GYS2, hepatic glycogen synthase deficiency, GSD 0a, depleted liver
glycogen, postprandial lactate/glucose changes, or absent hepatomegaly as a
distinguishing feature.
Concordance and completeness
Judgement: false-positive candidate; true GYS2/GSD 0a local gap.
The generated candidate is a carbohydrate-metabolism neighbor but it has an opposite glycogen-storage direction. IEMbase's disease reflects impaired liver glycogen synthesis and reduced hepatic glycogen, whereas GSD I reflects failure to mobilize glucose-6-phosphate and hepatic glycogen/fat accumulation. The absence of hepatomegaly and the fed lactate/glucose pattern make the GSD I candidate particularly misleading.
Curation actions
- Do not map this record to
Glycogen_Storage_Disease_Type_I.yaml. - Track GYS2-related hepatic glycogen synthase deficiency / GSD 0a as a local curation gap.
- Preserve IEMbase prompts for fasting avoidance, protein-rich diet, depleted liver glycogen, fed lactate/glucose, absent hepatomegaly, fasting hypoglycemia, and seizures for a future exact entry.