Figure 5.

Deficiency in COX activity within SN neurons revealed by COX/SDH histochemistry. Respiratory (COX)-deficient neurons were found in the SN of all patients with mitochondrial disease and controls used within this study. However, the COX-deficient neurons (blue) were sparse in patients with KSS/single large-scale deletion (this patient had only one COX-deficient neuron; A) and point mutations (B). POLG/multiple deletion patients (C) generally showed higher levels of COX deficiency than the patients with inherited defects. Few COX-deficient neurons were present in the controls (D). Images were taken at a 40× magnification. Scale bar, 100 μm. E, Percentage of respiratory/COX-deficient neurons in patients with mitochondrial diseases and controls compared with data from COXI immunohistochemistry. Error bars show SD of controls (n = 10). Due to a lack of tissue availability, we were unable to perform COX/SDH histochemistry on all patients.