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Acyl-CoA dehydrogenase, medium chain (MCAD)deficiency is an inborn error of mitochondrial fatty acid oxidation, inherited as an autosomal recessive trait. MCAD is an electron transfer flavoprotein (ETF)-dependant enzyme, located in mitochondrial internal matrix. Clinically, the disease is characterised by acute episodes of hypoketotic hypoglycemia with hepatomegaly (pseudo Reye syndrome), triggered by fasting or infections, which occur generally within the two first years of life. There is no muscle nor cardiac involvement. Diagnosis is suspected by a characteristic profile of urinary organic acids, plasma medium chain fatty acids and plasma acylcarnitines. A prevalent point mutation (A985G) has been identified (90% of muted alleles). The identification of this mutation and/or the measurement of MCAD activity in cultured fibroblasts allow to confirm the diagnosis. Treatment involves huge glucose infusion and eventually L-carnitine supplementation. The prognosis is good if fasting and catabolic states are avoided. |