3-Methylglutaconic and 3-methylglutaric aciduria in a patient with suspected 3-methylglutaconyl-CoA hydratase deficiency.

A girl suffering from marked muscular hypotonia, severe statomotor and mental retardation, bilateral optic atrophy with chorioretinal degeneration, convulsions and a moderate compensated metabolic acidosis is described. Screening for metabolic disorders revealed massive 3-methylglutaconic with 3-methylglutaric aciduria leading to the tentative diagnosis of 3-methylglutaconyl-CoA hydratase deficiency. Metabolite excretion was correlated with variation of leucine intake. 3-methyl-3-hydroxyglutaryl-CoA lyase activity in cultured fibroblasts was normal. The suspected metabolic defect was not demonstrable in cultured skin fibroblasts, however.