Together with other proteins, PURA forms density granules in diseases related to the RNA repeat expansion disorders, such as fragile X mental retardation protein (FMRP), encoded by FMR1 gene [19,28] and amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD) spectrum disorder [26,29]. The gene discussed is FMR1; the disease is amyotrophic lateral sclerosis.