Electron transfer flavoprotein: Ubiquinone oxidoreductase (ETF:QO) deficiency in an adult

A19-year-old woman with mild myopathic symptoms from age 6 and fasting intolerance presented with a Reye-like syndrome and a myopathy. Investigations disclosed a lipid storage myopathy, type II glutaric acidemia, and carnitine deficiency in skeletal muscle. Riboflavin and carnitine treatment corrected the metabolic abnormalities and she improved clinically. She later died from pulmonary complications secondary to aspiration. Subsequent studies established electron transfer flavoprotein:ubiquinone oxidoreductase (ETF:QO) deficiency (fibroblast ETF:QO activity was 2.9 mU/mg, normal range is 14.1 ± 3.8 mU/mg) as the cause of her illness. This is the first documented case of ETF:QO diagnosed in an adult.