[Late-onset riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency (glutaric aciduria type II)].

OBJECTIVE

Glutaric aciduria type II, or multiple acyl-CoA dehydrogenase deficiency is an autosomal recessively inherited defect of mitochondrial energy metabolism. The authors report two cases of late-onset glutaric aciduria type II, and evaluate the procedures for the diagnosis and treatment of this rare disease.

METHODS

The clinical and biochemical characteristics of 2 patients with late-onset glutaric aciduria type II were documented. Case 1 presented with lipid storage myopathy for 3 years. Case 2 presented with intermittent episodes of non-ketotic hypoglycemia and muscle weakness for 9 years. The diagnosis of the 2 cases was confirmed with gas chromatography/mass spectrometry analysis of urine samples. Riboflavin supplementation and a low-fat, low-protein, high-carbohydrate diet were initiated as soon as the diagnosis was made.

RESULTS

Organic acid analysis on both untreated cases revealed massive glutaric acid with elevated concentrations of isovalerylglycine, isobutyrylglycine, ethylmalonic acid, adipic acid, suberic acid and other dicarboxylic acids. The clinical manifestations were improved remarkably after the administration of riboflavin and diet control. Consistent improvements of sera enzymes and urine organic acids were observed during the course of treatment.

CONCLUSION

Patients with unexplained myopathy, metabolic acidosis or hypoglycemia should be carefully screened for inherited metabolic disorders. Riboflavin in conjunction with appropriate diet control is an effective therapeutic regime for patients with late-onset glutaric aciduria type II.