Oxidative phosphorylation (oxphos) is one of the most important functions of mitochondria, the power plants of the cell. oxphos is the oxidation of substrates and the production of energy as adenosine-triphosphate (atp). Defects of the oxphos-system form a group of diseases that are known as mitochondrial disorders. Most patients develop symptoms in infancy, especially muscle weakness, exercise intolerance and developmental delay. Lactic acid concentration in body fluids does not have to be elevated. Histopathological and especially biochemical investigations of muscle and fibroblasts are an essential part of the diagnostic process. In this report we describe biochemistry, molecular biology, clinical presentation, diagnostics and therapy of oxphos-system defects. The actual research topics of the Nijmegen Center for Mitochondrial Disorders are highlighted, focussing on complex I.
