Short-chain acyl coa dehydrogenase (SCAD) deficiency is an extremely rare inherited mitochondrial fatty acid oxidation disorder first reported in 1987. SCAD has been identified in only a few patients with highly variable clinical features, including (a) a lethal neonatal syndrome; (b) psychomotor retardation, muscle weakness, microcephaly, and poor feeding, all appearing during infancy; and (c) a myopathy in adulthood. Diagnosis may be based on the specific metabolite profile in blood and urine.