Late-onset multiple acyl-CoA dehydrogenase deficiency: A frequently missed diagnosis?

Abstract

Multiple acyl-CoA dehydrogenase (MAD) deficiency is caused by inherited deficiency of electron transfer flavoprotein (ETF) or ETF:ubiquinone oxidoreductase.1 The disease course is highly variable ranging from the neonatal (lethal) form with congenital abnormalities (type I), hypoglycemic encephalopathy without congenital abnormalities (type II), to myopathy (type III).1 Homozygosity for null mutations is usually associated with type I, whereas little residual activity is found in type II, and a relatively high residual activity in type III.2 Some patients with late-onset MAD deficiency have been reported previously but few have been described in detail.3,4 A 56-year-old man presented with progressive proximal myopathy of unknown origin. His family history and development were unremarkable. Before the onset of symptoms his exercise tolerance was unimpaired. His nutrition was predominantly based on animal products and was rich in fat and protein; alcohol abuse was not reported. At age 42 years he started having intermittent weakness and pain predominantly of the proximal limbs which was …