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Machado-Joseph disease type 1
Machado-Joseph disease type 1 is a rare, usually severe subtype of Machado-Joseph disease (SCA3/MJD, see this term) characterized by the presence of marked pyramidal and extrapyramidal signs.
ORPHA:276238Classification level: Subtype of disorder
- SCA3, Joseph type
- Spinocerebellar ataxia type 3, Joseph type
- Prevalence: Unknown
- Inheritance: Autosomal dominant
- Age of onset: Adult
- ICD-10: G11.8
- OMIM: -
- UMLS: C0751668
- MeSH: -
- GARD: -
- MedDRA: -
The prevalence of this form of MJD is not known. It accounts for 13% of all SCA3 cases.
Onset is generally early (mean of 24 years) and symptoms progress rapidly. MJD Type 1 patients generally present with cerebellar signs and external progressive ophthalmoplegia with variable degrees of pyramidal manifestations (spasticity, hyperreflexia). Patients also have extrapyramidal signs including dystonia.
The disease is caused by CAG repeat expansion mutations in the ATXN3 gene (14q21). Patients with this subtype of SCA3 tend to have larger CAG expansions than those with other subtypes.
MJD follows an autosomal dominant pattern of inheritance.