Machado–Joseph Disease, or Spinocerebellar Ataxia Type 3 (MJD/SCA3), is an inherited autosomal‐dominant disease of the brain that is genetically associated with CAG triplet expansion to over 55 repeats in the ATXN3 gene 1. This evidence concerns the gene ATXN3 and Spinocerebellar ataxia type 3.