These include an Ethe1−/− model of ethylmalonic encephalopathy (EE) [39], a Tymp−/− model of mitochondrial neuro-gastrointestinal encephalo-myopathy (MNGIE) [40,41], and Nr2f1−/− and OPA1delTTAG models for autosomal dominant optic atrophy (ADOA, BBSOA) [42,43] as well as an Ndufs4−/− model of Leigh syndrome [44,45]. The gene discussed is NDUFS4; the disease is ethylmalonic encephalopathy.