IEMbase 0300: GNPTG-related UDP-N-acetylglucosamine-1-phosphotransferase subunit gamma deficiency
Scope
| Field | Value |
|---|---|
| IEMbase ID | 300 |
| Nosology | 20.6.02.01 |
| Gene | GNPTG |
| External IDs | OMIM:252605; ORPHA:577 |
| Generated mapping | UNMAPPED |
| Candidate DisMech targets | GNPTG-Mucolipidosis.yaml |
| Review date | 2026-07-07 |
IEMbase phenotype signal
IEMbase represents GNPTG-CDG / mucolipidosis III gamma / pseudo-Hurler polydystrophy. Inheritance is autosomal recessive and treatability is unknown.
The cached clinical signal is sparse: joint contractures, recurrent otitis media, coarse facial features, and intellectual disability. Biochemical rows are more informative and show increased serum gamma-subunit/phosphotransferase readout, decreased leukocyte readout, normal-to-increased urinary glycosaminoglycans, and normal-to-increased urinary oligosaccharides.
DisMech phenotype coverage
GNPTG-Mucolipidosis.yaml is the correct local target despite the generated
UNMAPPED status. The local entry models biallelic GNPTG variants, gamma-subunit
impairment of GlcNAc-1-phosphotransferase, reduced mannose-6-phosphate tagging,
missorting and hypersecretion of lysosomal hydrolases, and slowly progressive
lysosomal substrate accumulation affecting skeletal, joint, and connective
tissues.
Local phenotypes include skeletal dysplasia, limitation of joint mobility, chronic pain, cardiac valve disease, carpal tunnel syndrome, restrictive lung disease, aortic valve insufficiency, motor delay, cognitive impairment, and autosomal recessive inheritance. Local treatments include supportive care, bisphosphonate therapy, joint replacement surgery, and pain management.
Concordance and completeness
Judgement: false negative; resolve to GNPTG-Mucolipidosis.yaml.
IEMbase and DisMech agree on GNPTG identity, recessive inheritance, ML III gamma scope, joint/connective-tissue involvement, coarse features, otitis, cognitive involvement, and the broader lysosomal enzyme-targeting mechanism. DisMech is richer for skeletal, pain, cardiac, carpal-tunnel, pulmonary, and management coverage.
IEMbase adds useful biochemical prompts, especially the serum-versus-leukocyte directionality and urinary glycosaminoglycan/oligosaccharide rows. The "(CDG)" label in IEMbase should be treated as alternate nomenclature context, not as a reason to separate this from GNPTG-mucolipidosis.
Curation actions
- Map this record to
GNPTG-Mucolipidosis.yaml. - Consider adding the IEMbase serum/leukocyte assay directionality and urinary GAG/oligosaccharide prompts if evidence supports them.
- Keep GNPTG ML III gamma distinct from GNPTAB-related mucolipidosis II and mucolipidosis III alpha/beta.