Mitochondria-lipid-glycogen myopathy, hyperlactacidemia, and carnitine deficiency

A 25-month-old girl had proximal myopathy, increased blood lactate and pyruvate concentrations, and transient ketoacidosis. Muscle biopsy revealed vacuolar myopathy with accumulation of both lipid and glycogen. Electronmicroscopy also showed abnormalities in the shape, size, and internal structure of muscle mitochondria. Carnitine content of skeletal muscle was reduced. Short-chain and long-chain acyl-carnitines were augmented in both plasma and skeletal muscle. Oral carnitine therapy improved muscle strength.