The<unk>  is caused by a mutation in the ATXN3 gene, which is located on chromosome 14q (14q32.1). In exon 10 the gene contains lengthy irregular repetitions of the code "CAG", producing a mutated protein called ataxin-3. (Normally, the number of copies is between 13 and 41.) MJD is an autosomal dominant<unk> , meaning that if either parent gives the defective gene to a child, the child will show symptoms of the<unk> . Therefore, if one parent suffers from this<unk>  and the other parent does not, there will be a 50% chance of their child inheriting the<unk> . The pons (a structure located on the brain stem) is one of the areas affected by MJD. The striatum (a brain area connected to balance and movement) is also affected by this<unk> , which could explain both of the main motor problems cause by MJD: the tightening and twisting of the limb and the abrupt, irregular movements. In affected cells, this protein builds up and assembles intranuclear inclusion bodies. These insoluble aggregates are hypothesized to interfere with the normal activity of the nucleus and induce the cell to degenerate and die.
Machado–Joseph disease
Darier's disease
Caroli disease
Borna disease
Lev's disease
Tornwaldt's disease
Marchiafava–Bignami disease
Bright's disease