Combined Oxidative Phosphorylation Defect Type 23

A rare mitochondrial disease characterized by early onset of hypertrophic cardiomyopathy and variable neurologic symptoms including global developmental delay, hypotonia, intellectual disability, visual impairment, and seizures. Lactic acidosis is present in all patients. Muscle biopsy usually shows decreased activity of mitochondrial complexes I and IV. Brain imaging may reveal variable abnormal signal intensities in the thalamus, basal ganglia, and/or brain stem.