HTT and spinocerebellar ataxia type 2: Notably, several other neurological conditions with cognitive and motor involvement are associated with polyQ expansions: huntingtin in Huntington's disease (3), ATAXIN-2 in spinocerebellar ataxia 2 (SCA2) (4) and its pre-mutation expansion with Amyotrophic lateral sclerosis (ALS) (5, 6), Atrophin-1 in Dentatorubral pallidoluysian atrophy (DRPLA) and several genes implicated in distinct types of spinocerebellar ataxia (4).