NOTCH2NLC Intermediate‐Length Repeat Expansions Are Associated with Parkinson Disease

NOTCH2NLC GGC repeat expansions were recently identified in neuronal intranuclear inclusion disease (NIID); however, it remains unclear whether they occur in other neurodegenerative disorders. This study aimed to investigate the role of intermediate‐length NOTCH2NLC GGC repeat expansions in Parkinson disease (PD). We screened for GGC repeat expansions in a cohort of 1,011 PD patients and identified 11 patients with intermediate‐length repeat expansions ranging from 41 to 52 repeats, with no repeat expansions in 1,134 controls. Skin biopsy revealed phospho‐alpha‐synuclein deposition, confirming the PD diagnosis in 2 patients harboring intermediate‐length repeat expansions instead of NIID or essential tremor. Fibroblasts from PD patients harboring intermediate‐length repeat expansions revealed NOTCH2NLC upregulation and autophagic dysfunction. Our results suggest that intermediate‐length repeat expansions in NOTCH2NLC are potentially associated with PD. ANN NEUROL 2021;89:182–187