ETFDH and multiple acyl-CoA dehydrogenase deficiency: The diagnosis of MADD is typically indicated by elevated levels of several acylcarnitine species in the blood and increased excretion of multiple organic acids in the urine, confirmed through the identification of biallelic pathogenic variants in the genes encoding electron transfer flavoprotein α(ETFA), electron transfer flavoprotein β(ETFB), or electron transfer flavoprotein dehydrogenase (ETFDH) [2].