A survey on inborn errors of metabolism in 323 neonates from the state of Rio de Janeiro, Brazil.

Inborn errors of metabolism (IEM) are a relevant cause of morbidity and death among children, and neonates in particular. However, little is known about the prevalence of these disorders in Brazilian newborns. Our laboratory of IEM (LABEIM) at the Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro (UFRJ), has been working on the diagnosis of IEM since 1988. Out of 3,300 patients (90% children), screened and evaluated from 1989 to 2,000 because of a high clinical suspicion of having an IEM, 323 (9.8%) were neonates. Patients came from different regions of the state of Rio de Janeiro, in which lives approximately 8.5% of the total Brazilian population. Chemical tests, various chromatographic techniques and enzyme assays were performed in urine, plasma and in some cases, cerebrospinal fluid (CSF). This study describes our laboratory and the experience with the 323 investigated neonates, among which 28 cases (8.7%) of IEM were identified and 18 (5.6%), strongly suspected. All these cases were related mainly to the metabolism of amino acids, organic acids, lysosomal enzymes and carbohydrates. Furthermore, data on population, community and health services are presented.