The RNA-binding protein (RBP) fused in sarcoma (FUS) forms cytoplasmic aggregates in variants of both amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD; Kwiatkowski et al., 2009; Neumann et al., 2009; Vance et al., 2009), neurodegenerative diseases that are extremes of one disease spectrum (Ragagnin et al., 2019). The gene discussed is FUS; the disease is frontotemporal dementia.