IEMbase 0353: POMT2-related muscular dystrophy-dystroglycanopathy
Scope
| Field | Value |
|---|---|
| IEMbase ID | 353 |
| Nosology | 18.2.02.02 |
| Gene | POMT2 |
| External IDs | OMIM:613150; OMIM:613156; OMIM:613158; ORPHA:899 |
| Generated mapping | UNMAPPED; low candidate Dystroglycanopathy.yaml |
| Candidate DisMech targets | Dystroglycanopathy.yaml#MDDG2/POMT2 |
| Review date | 2026-07-07 |
IEMbase phenotype signal
IEMbase represents POMT2-CDG/muscular dystrophy-dystroglycanopathy type A2, type B2, and type C2, an autosomal recessive O-mannosylation disorder. Characteristic rows include buphthalmos, cerebral cortical malformations, increased creatine kinase, glaucoma, megalocornea, microphthalmia, muscular dystrophy, pigmentary retinopathy, psychomotor delay, normal sialotransferrins, and Walker-Warburg syndrome.
Additional clinical rows include corpus callosum agenesis on MRI, cataract, cerebellar abnormalities, cobblestone lissencephaly, dysmorphic features, encephalocele, epilepsy, exophthalmia, fatal evolution before 1 year, and hydrocephalus. Biochemical rows include creatine kinase, matriglycan-specific monoclonal antibody, and sialotransferrins. No treatment rows are present.
DisMech phenotype coverage
The generated UNMAPPED status is a false negative. DisMech has a Dystroglycanopathy file that explicitly covers muscular dystrophy-dystroglycanopathy types A/B/C and the POMT2/MDDG2 subtype. Local mechanism describes defective O-mannosyl glycosylation of alpha-dystroglycan; POMT2 forms the POMT1-POMT2 enzyme complex required for the first O-mannosylation step and can produce the full type A/B/C severity spectrum.
Local coverage includes muscular dystrophy, proximal weakness, neonatal hypotonia, elevated serum CK, cobblestone lissencephaly, intellectual disability, retinal dysplasia, hydrocephalus, seizures, reduced alpha-dystroglycan glycosylation, reduced laminin binding, supportive rehabilitation, genetic counseling, and emerging ribitol/AAV therapeutic context.
Concordance and completeness
Judgement: false negative; resolve to the local dystroglycanopathy POMT2 subtype.
The resources agree on POMT2 identity, autosomal recessive inheritance, O-mannosylation/alpha-dystroglycan biology, Walker-Warburg/type A severe spectrum, muscular dystrophy, elevated CK, cortical/cobblestone brain malformations, hydrocephalus, seizures, ocular involvement, psychomotor delay, and early lethality in the severe end.
Curation actions
- Map this record to
Dystroglycanopathy.yaml, specifically the POMT2/MDDG2 subtype context. - Consider future enrichment with buphthalmos, megalocornea, microphthalmia, cataract, glaucoma, pigmentary retinopathy, corpus callosum agenesis, encephalocele, fatal-before-1-year wording, and matriglycan antibody testing after source verification.
- Treat absent IEMbase treatment rows as incomplete IEMbase coverage rather than a contradiction of local supportive and investigational therapy context.