MT-ND2 and Leigh syndrome: Because mutations in human ND2 have been demonstrated to cause Leigh syndrome (Ugalde et al., 2007), Leber’s hereditary optic neuropathy (Brown et al., 1992) and exercise intolerance (Schwartz and Vissing, 2002), we hypothesized that Drosophila ND2 mutants might serve as an animal model of complex-I-associated disease.