TARDBP and spinocerebellar ataxia type 2: Ataxin 2 (ATXN2), an RBP that when mutated by polyglutamine (polyQ) expansion causes spinocerebellar ataxia type 2 (SCA2) (3, 4, 5, 6), was shown to bind to the amyotrophic lateral sclerosis (ALS)–linked Tar DNA-binding protein 43 (TDP-43) (7).