Machado–Joseph disease (also known as Spinocerebellar ataxia type 3) is caused by polyQ expansions of Ataxin-3, and it was shown that the mutant disease protein does not undergo aggregation in fibroblasts, induced pluripotent stem cells, glia cells, but only in neurons after stimulation by glutamate in processes that depended on Ca2+ [92]. Here, ATXN3 is linked to Spinocerebellar ataxia type 3.