C9orf72 and fragile X-associated tremor/ataxia syndrome: Several lines of evidence indicate that RAN translated proteins are involved in a growing number of microsatellite repeat expansion diseases, including HD, DM1, SCA8, FXTAS, and C9orf72-ALS/FTD (Banez-Coronel and Ranum, 2019; Nguyen et al., 2019).