A novel ETFDH mutation identified in a patient with riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency

Lipid storage myopathies (LSM) are a group of inherited metabolic muscle disorders characterized by abnormal lipid metabolism and the deposition of lipids within muscle fibers. Multiple acyl-coenzyme A dehydrogenase deficiency (MADD) is the most common type of LSM in China, caused by mutations in the gene expressing electron transfer flavoprotein dehydrogenase (ETFDH). Here, we report a 14-year-old girl presenting with exercise intolerance, followed by muscle weakness and pain. Initially, the patient showed rhabdomyolysis (RML) and was misdiagnosed with polymyositis (PM). However, muscle biopsy and genetic analysis led to a diagnosis of MADD. After the initiation of vitamin B2 administration, her symptoms were rapidly ameliorated. Genetic testing revealed compound heterozygous mutations in the ETFDH gene, specifically c.250G>A and c.929A>G, the second of which has not previously been reported. In conclusion, we report a novel mutation of ETFDH in a patient with riboflavin-responsive MADD, which expands our knowledge of MADD-related gene variants in the Chinese population.