HTT and Huntington disease: Huntingtin fragments have been reported to be in close apposition to mitochondria in cellular and animal models of HD (Gutekunst et al., 1998; Choo et al., 2004; Orr et al., 2008) as well as in brain mitochondria of the caudate nucleus of HD patients (Yano et al., 2014) suggesting a direct role of mutant huntingtin in mitochondrial dysfunction.