Adult-onset neuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative disorder with a heterogeneous clinical presentation that can mimic stroke and various forms of dementia. To date, it has been described almost exclusively in Asian individuals.
Case presentation including MRI imaging of the neurocranium, histology by skin biopsy and long-read genome sequencing.
A 75-year-old Caucasian female presented with paroxysmal encephalopathy twice within a 14-month period. Brain MRI revealed high intensity signals at the cerebral corticomedullary junction (DWI) and the paravermal area (FLAIR), a typical distribution observed in adult-onset NIID. The diagnosis was corroborated by skin biopsy, which demonstrated eosinophilic intranuclear inclusion bodies and confirmed by long-read genome sequencing, showing an expansion of the GGC repeat in exon 1 of NOTCH2NLC.
Our case proves adult-onset NOTCH2NLC-GGC-positive NIID with typical findings on MRI imaging and histology in a Caucasian patient and underscores the need to consider this diagnosis in non-Asian individuals as well.
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