The relevance of complex II dysfunction in HD is highlighted by the fact that mutant huntingtin leads to decreased expression (at the protein level) of the 30 kDa iron-sulfur (Ip) subunit and the 70 kDa FAD (Fp) subunit of complex II in the striatum of HD patients [153] and in vitro lentiviral models [153, 154]. Here, HTT is linked to Huntington disease.