ARRB2 and early-onset autosomal dominant Alzheimer disease: ARRB2 encodes β-arrestin 2, which regulates various signaling pathways, including those involved in cell survival and apoptosis processes that are important in the pathophysiology of neurodegenerative diseases, such as Alzheimer’s disease (AD) [51, 52], frontotemporal dementia (FTD) [53], and Parkinson’s disease (PD) [54].