The series of encoded proteins (Ndufa12, Ndufa5, Ndufb9, etc) are subunits of the NADH: ubiquinone oxidoreductase (complex I) which is part of the oxidative phosphorylation system in mitochondria, participate in oxidative phosphorylation, thermogenesis, Non-alcoholic fatty liver disease (NAFLD) and diseases of Alzheimer, Parkinson, Huntington. This evidence concerns the gene NDUFA5 and early-onset autosomal dominant Alzheimer disease.