Conclusion: This approach may be a useful primary screening method for low-or high-excretor variants in populations with high risk of GA1. Furthermore, for babies with elevated dried blood spot C5DC, follow-up testing of DUS GA and 3HGA will be a useful diagnostic test that may reduce the number of cases requiring enzymatic and molecular analyses. Background: The pathogenesis of the brain damage in glutaric acidemia type I (GA I) is not well understood. Objectives: Relevant oxidative stress parameters were investigated in cerebral cortex, striatum, hippocampus, liver and heart of 30-day-old knockout mice with glutaryl-CoA dehydrogenase deficiency (Gcdh −/−) and in wild-type animals (Gcdh +/+). Methods: Tissues were dissected, homogenized and assayed biochemically. Some Gcdh −/− and Gcdh +/+ mice received 8 μmol/g L-lysine i.p. 24 hours before the assays were performed. Results: Significant changes were observed only in the brain of Gcdh −/− mice that had received lysine, which is converted to glutaric and 3hydroxyglutaric acids. Cerebral cortex in these animals showed significantly higher thiobarbituric reactive acid substances (TBA-RS) and superoxide dismutase (SOD) activity and a diminution of reduced glutathione (GSH). In the striatum, TBA-RS, SOD and glutathione reductase were increased, while GSH levels and glutathione peroxidase activities were decreased. SOD activity was increased in the hippocampus. No changes were observed in liver and heart. Conclusions: Brain, and especially striatum, in Gcdh −/− mice is more vulnerable to oxidative stress following lysine administration than liver and heart. Increased vulnerability to oxidative stress may contribute to the pathogenesis of brain damage in human GA I. Case Report: We report three Iranian patients with GA1. All of them were from first cousin Iranian parents; had prolonged physiological Icter and macrocephaly. All three had highly elevated C5DC, glutaric acid and 3hydroxy glutaric acid. Two sibling were found to be homozygous for the GCDH gene mutation in the exon10 position390 (P.Gly390Ala). Surprisingly, in spite of similar mutation the 4 years old girl showed normal development without treatment whereas the development of her 15 months brother was severely impaired. The third patient, a 3 years old girl, was found to be homozygous for the GCDH gene mutation in the exon6 position 179 (C179Leu>Pro). Conclusion: If not diagnosed early and treated preventively before recurrent encephalopathic crisis occur, GA type1 is usually associated with a severe irreversible neurologic syndrome. This report indicates examination of urinary organic acid and acyl carnitine profile in children with symptoms of developmental delay and macrocephaly. Background: GA II is a disorder of fatty and amino acids metabolism due to defects of the Electron Transfer Flavoprotein (ETF) or ETF-CoQ oxidoreductase (ETF-QO). The disease is widely variable in its symptoms, severity, age of onset and rate of progression. Brain MRI typically shows T2-weighted hyperintensity of basal ganglia.