Neuronal intranuclear inclusion disease presenting with an MELAS-like episode in chronic polyneuropathy

Neuronal intranuclear inclusion disease (NIID) exhibits diverse clinical phenotypes caused by the intronic repeat expansion of NOTCH2NLC .1,2 An acute encephalopathic episode can manifest in some patients with NIID.3,4 Herein, we report an NIID patient harboring a de novo {(GGA)n(GGC)n}n repeat expansion in NOTCH2NLC , who developed abrupt mitochondrial encephalomyopathy, lactic acidosis, and stroke-like (MELAS)-like episode in the 15-year course clinical diagnosed as chronic inflammatory demyelinating polyneuropathy (CIDP).