FMR1 and fragile X-associated tremor/ataxia syndrome: Furthermore, FXTAS and NIID are neurodegenerative diseases, but FMR1 and NOTCHNLC expression are not restricted to neurons, and intranuclear inclusions are widely observed outside of the CNS in individuals with FXTAS and NIID (Greco et al., 2006; Hunsaker et al., 2011; Yamaguchi et al., 2018; Chen H. et al., 2020).