NOTCH2NLC and neuronal intranuclear inclusion disease: OPDM3 and neuronal intranuclear inclusion disease (NIID) share the same cause, GGC repeat expansions in NOTCH2NLC. The pathological process of OPDM3 extends beyond the oculopharyngeal muscles, and involves various extraskeletal muscle organs, including the central and peripheral nervous systems, as well as cardiac, respiratory, and gastrointestinal systems (Ishiura et al., 2019; Tian et al., 2019; Ogasawara et al., 2020; Cao et al., 2021; Yu et al., 2021a; Yu et al., 2021b; Boivin and Charlet-Berguerand, 2022; Huang et al., 2022; Ma et al., 2024).