Niemann-Pick Type C 1 (NPC1) and NPC2 gene variability in demented patients with evidence of brain amyloid deposition

Background: Variants in Niemann-Pick Type C genes (NPC1 and NPC2) have been suggested to play a role as risk or disease modifying factors for Alzheimer's disease (AD). Objective: The aim of this study was to analyze NPC1 and NPC2 variability in demented patients with evidence of brain amyloid-β 1-42 (Aβ) deposition and to correlate genetic data with clinical phenotypes. Methods: A targeted Next Generation Sequencing panel was customized to screen NPC1, NPC2, and main genes related to neurodegenerative dementias in a cohort of 136 demented patients with cerebrospinal fluid (CSF) low Aβ levels or positive PET with Aβ tracer and 200 non-demented geriatric subjects. Results: Seven patients were carriers of NPC variants in heterozygosis. Four of them displayed pathogenic variants previously found in NPC patients and one AD patient had a novel variant. The latter was absent in 200 non-demented elderly subjects. Five of seven patients (70%) exhibited psychiatric symptoms at onset or later as compared with 43%in non-carriers (p > 0.05). Conclusion: The frequency of NPC1 and NPC2 heterozygous variants in patients with CSF evidence of Aβ deposition is higher than in the general population.