Combined oxidative phosphorylation defect type 23 Hannah McLaren COXPD23 Orphanet:444013 OMIM:616198 Combined oxidative phosphorylation defect type 23 is an autosomal recessive disorder characterized by early childhood onset of hypertrophic cardiomyopathy and/or neurologic symptoms, including hypotonia and delayed psychomotor development. Laboratory investigations are consistent with a defect in mitochondrial function resulting in lactic acidosis, impaired activities of respiratory complexes I and IV, and defective translation of mitochondrial proteins. Brain imaging shows abnormal lesions in the basal ganglia, thalamus, and brainstem. The severity of the disorder is variable, ranging from death in early infancy to survival into the second decade (summary by Kopajtich et al., 2014). Mitochondrial disorder due to a defect in mitochondrial protein synthesis