Complex III Deficiency
Long Name: Ubiquinone-cytochrome c oxidoreductase deficiency
Symptoms: Four major forms:
Fatal infantile encephalomyopathy, congenital lactic acidosis, hypotonia, dystrophic posturing, seizures, and coma. Ragged-red fibers common.
Encephalomyopathies of later onset (childhood to adult life): various combinations of weakness, short stature, ataxia, dementia, hearing loss, sensory neuropathy, pigmentary retinopathy, and pyramidal signs. Ragged-red fibers common. Possible lactic acidosis.
Myopathy, with exercise intolerance evolving into fixed weakness. Ragged-red fibers common. Possible lactic acidosis.
Infantile histiocytoid cardiomyopathy
Treatment: As with all mitochondrial diseases, there is no cure for Complex III deficiency. A variety of treatments, which may or may not be effective, can include such metabolic therapies as: riboflavin, thiamine, biotin, co-enzyme Q10, carnitine, and the ketogenic diet. Therapies for the infantile multisystem form have been unsuccessful.
Cause: Probably autosomal recessive
Links: https://rarediseases.info.nih.gov/diseases/8295/mitochondrial-complex-iii-deficiency