Spinocerebellar ataxia 3

Machado Joseph disease, also called spinocerebellar ataxia 3, is an inherited movement disorder. It is not a form of Parkinson's disease. Some people with spinocerebellar ataxia type 3 have symptoms that are similar to Parkinson's disease, such as such as slowness of movement, stiffness of the limbs and trunk, trembling hands, and impaired balance and coordination.^[1] These affected individuals may be described as having "parkinsonism," which refers to any condition that causes Parkinson's-type abnormal movements.^[2]

Spinocerebellar ataxia 3 (SCA3) is a rare, inherited form of ataxia. Signs and symptoms may begin between childhood and late adulthood and vary greatly. Symptoms may include slowly progressive clumsiness in the arms and legs; a manner of walking (gait) that may be mistaken for drunkenness; difficulty speaking and swallowing; impaired eye movements or vision; and lower limb spasticity. Some people with SCA3 develop dystonia or symptoms similar to those of Parkinson’s disease; twitching of the face or tongue; nerve damage (neuropathy); or problems with urination and the autonomic nervous system.^[1]

SCA3 is caused by a mutation in the ATXN3 gene and inheritance is autosomal dominant. There is no medication that slows the progressive course of the disease; management aims to relieve some symptoms and improve quality of life.^[3] Life expectancy ranges from the mid-30s for those with the most severe forms, to a nearly normal life expectancy for those with milder forms.^[1]