Humanin has a molecular weight of 2687.26 Da and is encoded from a small open reading frame within the 16S ribosomal RNA gene, MT-RNR2, of the mitochondrial genome.16 Humanin is cytoprotective against amyloid-β induced 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, Huntington’s disease, and Prion diseases.21, 22, 23 Moreover, Humanin rescues primary RPE cells from oxidative damage and subsequent death in vitro. Here, MT-RNR2 is linked to juvenile Huntington disease.