Definition:

Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), is one of the most common hereditary ataxias and is distributed worldwide. MJD is an autosomal dominant neurodegenerative disorder, involving predominantly the cerebellar, pyramidal, extrapyramidal, motor neuron and oculomotor systems. Minor, but more specific, features such as external progressive ophthalmoplegia (EPO), dystonia, intention fasciculation-like movements of facial and lingual muscles, as well as bulging eyes, may also be of major importance for the clinical diagnosis of MJD. The mean age at onset is around 40 years. MJD is associated with CAG repeat expansions in the ATXN3 gene. CAG repeat varies in size among affected persons. There is no effective treatment of ataxia. Case series and small controlled trials of several medications including antianxiolytics, antidepressants, and antiepileptics have shown limited efficacy.