A rare, genetic, mitochondrial oxidative phosphorylation disorder characterized by a wide spectrum of clinical manifestations ranging from isolated myopathy or transient hepatopathy to severe multisystem disorder (that may include hypotonia, failure to thrive, psychomotor delay, cardiomyopathy, encephalopathy, renal tubulopathy, hearing impairment, lactic acidosis, hypoglycemia and other signs and symptoms). The disease is MONDO_0015448 (mitochondrial complex III deficiency). Also known as: isolated CoQ-cytochrome C reductase deficiency, isolated coenzyme Q-cytochrome C reductase deficiency, isolated mitochondrial respiratory chain complex III deficiency, isolated ubiquinone-cytochrome C reductase deficiency, mitochondrial respiratory chain complex III deficiency.