Multiple FAD dehydrogenase deficiency, also known as glutaric aciduria type II, impairs fatty acid oxidation, and also stops the oxidation of branched aminoacids, lysine and glutaric acid. Complete deficiency causes severe disorders in neonates, including acidosic coma without ketosis, hypoglycemia, hyperammonemia, hypotonia, myocardiopathy, and sometimes congenital malformations (polycystic kidneys, dysmorphic facies). Juvenile, adolescent or even adult forms have been reported but are less severe, with progressive myocardiopathy or proximal myopathy. The disease is due to a defective electron transfer flavo protein or electron transfer flavo protein dehydrogenase. Chromatography of urinary organic acids and plasmatic acyl carnitines is suggestive of the disease, showing dicarboxylic aciduria, glutaric and ethylmalonic aciduria and suberylglycine. Total carnitine levels are very low. Multiple FAD dehydrogenase deficiency (MADD) is transmitted as an autosomal recessive trait. Diagnosis is confirmed by the in vitro study of fatty acid oxidation in lymphocytes or fibroblasts and enzymatic activity. Prenatal diagnosis is available. Patients should eat regularly and limit their protein intake to moderate amounts, while fatty foods should be avoided. Carnitine is systematically given. Some cases are riboflavine sensitive (cofactor of FAD dehydrogenases).
Last update: March 2004