Humanin has been shown to have multiple neuro- and cytoprotective functions, including increased survival and protection against oxidative stress in in vitro and in vivo models for AD, stroke, and Huntington’s disease [47–51], and suppression of apoptosis by binding to the protein Bax and blocking Bax translocation from the cytosol to mitochondria [45]. Here, MT-RNR2 is linked to juvenile Huntington disease.