Adult‐onset neuronal nuclear inclusion disease presenting with mental and behavioral disorders: A case report and literature review

Neuronal nuclear inclusion disease (NIID) is a rare neurological degenerative disease,1 and it typically presents with chronic or subacute onset. The clinical manifestations of NIID are highly heterogeneous and include disturbance of consciousness, seizures, motor and sensory abnormalities, dementia, ataxia, peripheral neuropathy, and autonomic dysfunction. These symptoms are often misdiagnosed as other nervous system diseases. At present, the etiology and pathogenesis of NIID are not clear. Immunohistochemical studies showed that eosinophilic inclusion bodies were positive for ubiquitin and ubiquitinrelated proteins, including P62, SUMO1, FUS, MYO6, and OPTNC, suggesting that the ubiquitin– proteasome pathway may play a role in the pathogenesis of NIID.2– 5 In recent years, studies in NIID families have found that GGC sequence in the 5′ region of the humanspecific NOTCH2NLC gene, which is the pathogenic gene of adultonset NIID, is abnormally repeated, so the NOTCH2NLC gene is associated with the pathogenesis of familial NIID.6– 9