ETFDH and Lipid storage disease: Multiple acyl-CoA dehydrogenase deficiency (MADD) is a lipid metabolism disorder caused by defects in electron transfer flavoprotein or electron transfer protein dehydrogenase, encoded by ETFA, ETFB, and ETFDH. MADD is the most prevalent lipid storage disease in Taiwan, where the hotspot mutation ETFDH c.250G > A has a carrier frequency of 0.8% [1].