MT-RNR2 and early-onset autosomal dominant Alzheimer disease: Humanin is cytoprotective against amyloid-β-mediated toxicity in neuronal cells, both in vitro and in vivo [17,18]; against cerebral ischemia and cardiac damage in mouse models [19,20]; and in numerous neurodegenerative disease models for Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and Prion diseases [18,19,39,40].