Fulminant lipid storage myopathy due to multiple acyl‐coenzyme a dehydrogenase deficiency

: The lipid storage myopathies, primary carnitine deficiency, neutral lipid storage disease, and multiple acyl coenzyme A dehydrogenase deficiency (MADD), are progressive disorders that cause permanent weakness. These disorders of fatty acid metabolism and intracellular triglyceride degradation cause marked fat deposition and damage to muscle cells. Methods : We describe a rapidly progressive myopathy in a previously healthy 33‐year‐old woman. Over 4 months, she developed a proximal and axial myopathy associated with diffuse myalgia and dysphagia, ultimately leading to respiratory failure and death. Results : Muscle biopsy showed massive accumulation of lipid. Plasma acylcarnitine and urine organic acid analysis was consistent with MADD. This was confirmed by molecular genetic testing, which revealed 2 pathogenic mutations in the ETFDH gene. Conclusions : This report illustrates a late‐onset case of MADD and reviews the differential diagnosis and evaluation of patients with proximal myopathy and excessive accumulation of lipid on muscle biopsy. Muscle Nerve 52 : 289–293, 2015