HTT and Huntington disease: We recently found that inhibition of excessive mitochondrial fission (but not physiological fission) by a selective inhibitor of the mitochondrial fission protein, dynamin-related protein 1 (Drp1), prevents mutant huntingtin-induced pathology in vitro and in vivo (Guo et al, 2013), suggesting that mitochondrial dynamics is a potential therapeutic target for HD.