ATXN3 and Spinocerebellar ataxia type 3: Spinocerebellar ataxia type 3 (SCA3), also known as Machado–Joseph disease (MJD), is an autosomal dominant neurodegenerative disease, caused by the expansion of a repetitive CAG sequence in the ATXN3 gene located on chromosome 14q32 (1, 2).