[Generalized epilepsy disclosing medium-chain-acyl-CoA dehydrogenase deficiency]

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is the most common inherited defect of fatty acid beta-oxidation. As it causes life-threatening symptoms, it is mandatory to diagnose deficiencies of this enzyme in families.

A boy was admitted at the age of 3 months because of a recent attack of generalized seizures. His parents were second cousins and one of his 2 sisters, 6 years old, suffered from epilepsy. At admission, the patient had moderate hepatomegaly; he was given clonazepam and phenytoin because of persistent status epilepticus. He developed a fever (temp.: 39 degrees) and a rash 24 hours later. A viral etiology was suggested by CSF contents of 104 cells/mm3 and 1 g/l protein. The patient was given aciclovir. Blood glucose, transaminases, ammonia, lactate, pyruvate and amino acids levels were normal. Analysis of urine by GC-MS revealed a large lactate peak and dicarboxylic acids, unsaturated dicarboxylic acids, hydroxyhexanoate, 7-hydroxyoctanoate, hexanoylglycine and suberylglycine. This profile indicated a MCAD deficiency. The plasma contained partially oxidized medium-chain fatty acids, such as octanoic acid and especially 4-decenoic acid. the diagnosis was confirmed by a phenylpropionate loading test and specific enzyme assay in fibroblasts. Molecular studies identified a G 985 mutation in the patient and revealed that the parents were heterozygotes for the mutation. The condition of the patient at the age of 18 months is excellent; he has a regular, adequate caloric intake and avoids fasting. He has not taken anti-epileptic drugs for the past 6 months.

There is no typical clinical presentation of MCAD-deficiency; the most frequent features are vomiting and lethargy. Episodic hypoglycemia has been reported, but hypoglycemia was not found in our patient. Molecular studies will allow neonatal diagnosis of the next affected siblings.