INS and early-onset autosomal dominant Alzheimer disease: Growing evidence implicates abnormal insulin signaling in the pathogenesis of Alzheimer’s disease (AD), a neurodegenerative condition whose fundamental feature is β-amyloid (Aβ) and tau protein deposition in the brain (De La Monte and Wands, 2008; Ahmad, 2012; Jahangir et al., 2014; Sridhar, 2015; Ribes-Navarro et al., 2018).