PURA has been implicated in two different nucleotide-repeat expansion disorders: fragile X-associated tremor/ataxia syndrome (FXTAS) and the disease continuum of C9orf72-mediated amyotrophic lateral sclerosis and fronto-temporal dementia (C9 ALS/FTD). The gene discussed is PURA; the disease is fragile X-associated tremor/ataxia syndrome.