FMR1 and neuronal intranuclear inclusion disease: The diagnosis of NIID was established on the basis of the following key findings: diffusion-weighted imaging revealed a characteristic "crown-like" hyperintensity at the corticomedullary junction; genetic analysis revealed a GGC repeat expansion in the <i>NOTCH2NLC</i> gene, with no abnormalities detected in <i>FMR1</i>; and skin biopsy demonstrated p62-positive intranuclear inclusions within sweat gland cells.