While cytoplasmic aggregation of FUS has so far only been linked with the pathogenesis of ALS and FTD, a number of immunohistochemical and mass spectrometry-based studies have also reported FUS in intranuclear neuronal inclusions that accumulate in polyglutamine repeat expansion disorders, including HD, spinocerebellar ataxia type 1 and 3 (SCA 1 and SCA 3), and a rare multisystem neurodegenerative condition termed neuronal intranuclear inclusion body disease (NIIBD) [132–135]. This evidence concerns the gene FUS and amyotrophic lateral sclerosis.