Background: Glutaryl-CoA dehydrogenase deficiency (GDD) is a recessively inherited neurometabolic disorder associated with encephalopathic crises and severe extrapyramidal symptoms. Treatment regimens including glucose and electrolyte infusions during acute illnesses, oral carnitine supplementation and/or a low-protein or lysine-restricted diet have been recommended, but their efficacy has been documented only on an anecdotal basis.
Subjects and methods: We conducted a retrospective analysis of 57 patients with proven GDD-relating appearance and severity of neurological disease to age and clinical status at diagnosis, glutaric acid levels in body fluids, and different treatment regimens.
Results: Thirty-six patients were diagnosed after the onset of neurological disease (symptomatic group), twenty-one before (presymptomatic group). Carnitine levels were found to be reduced in all patients at diagnosis. In the symptomatic group, macrocephaly had been present around birth and was followed by rapid postnatal head growth in 70% of the children. The patients often showed symptoms such as hypotonia, irritability, and jitteriness followed by an acute encephalopathic crisis occurring on average at 12 months of age. Common neuroimaging findings included frontotemporal atrophy, subependymal pseudocysts, delayed myelination, basal ganglia atrophy, chronic subdural effusions and hematomas. In four patients the latter two findings were initially misinterpreted as resulting from child abuse. Other important misdiagnoses in older siblings who were affected and went undiagnosed include postencephalitic cerebral palsy, dystonic cerebral palsy and sudden infant death syndrome. Metabolic treatment did not convincingly improve the neurological disease, although it may have prevented further deterioration. Symptomatic treatment with baclofen or benzodiazepines was effective in reducing muscle spasms. Children in the presymptomatic group were diagnosed because of familiarity for the disease (n = 13), macrocephaly and/or additional minor neurological signs in infancy (n = 6), or acute encephalopathy, which was fully reversible after prompt treatment (n = 2). After diagnosis, all children were treated with oral carnitine, fluid infusion during intercurrent illnesses and, in addition, a diet was started in 13 of the 21 children. All 21 children except one (born prematurely at 31 weeks) have continued to develop normally up to now. Mean age at report is 6.3 years with a range from 6 months to 14.8 years. In older patients, the neuroradiological changes, present in infancy as in the symptomatic patients, became less prominent and in one girl disappeared.
Conclusions: In presymptomatic children with GDD, the onset of neurological disease can be prevented by vigorous treatment of catabolic crises during illnesses together with carnitine supplementation. The importance of dietary therapy remains unclear and needs further evaluation. The potential treatability of GDD calls for increased attention to early presenting signs in order to recognize the disorder and to initiate treatment before the onset of irreversible neurological disease.