High Quality Content by WIKIPEDIA articles! Machado–Joseph disease (MJD) or Spinocerebellar ataxia type 3 (SCA3) is a rare autosomal, dominantly inherited neurodegenerative disease that causes progressive cerebellar ataxia, which results in a lack of muscle control and coordination of the upper and lower extremities. The symptoms are caused by a genetic mutation that results in an expansion of abnormal "CAG" trinucleotide repeats in the ATXN3 gene that results in degeneration of cells in the hindbrain. Some symptoms, such as clumsiness and rigidity, make MJD commonly mistaken for drunkenness and/or Parkinson`s disease.