INTRODUCTIONInborn errors of metabolism (IEMs) are a group of genetic disorders that result in a structurally or functionally altered protein, resulting in a block in a metabolic pathway. Several hundred hereditary metabolic disturbances are known, many of which correspond to grave illnesses that frequently evolve to death or cause mental deficiency.
1Several groups of IEMs typically present with acute life threatening symptoms of acute encephalopathy and epilepsy as a result of toxic effects of accumulating metabolites on the central nervous system. 2 Studies in Nepal have shown a prevalence of neonatal encephalopathy of 6.1 per thousand births 3 while a community survey showed the prevalence of epilepsy to be 7 per 1000 population. 4 IEMs in Nepal have been reported as cases in literature and their prevalence in the Nepalese population is unknown.This study was undertaken to initiate an investigation regarding the existence of IEMs in the Nepalese population beginning with mentally retarded children. Noninvasive, simple and inexpensive chemical methods of screening urine for abnormal metabolites were used.
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METHODSEthical clearance for carrying out the IEM urinalysis was obtained from Nepal Health Research Council, Ministry of Health & Population, Kathmandu and samples were obtained only with consent of parents or guardians. Random urine samples were obtained from a total of 62 children from the Association for the Welfare of Mentally Retarded (AWMR) in Sinamangal and Navajyoti Centre (School for Mentally Handicapped Children), Baluwatar, both situated in Kathmandu, Nepal over a period of eight months (Jan 2012 -August 2012).A subpopulation of children with mental retardation was selected at the two institutions. This group of children had a higher probability of the presence of IEM. The volume of urine collected was variable and was sufficient to perform the tests at least once. The volume of urine needed to perform each test was calculated from the urinary creBackground: Most inborn errors of metabolism result in mental retardation and death due to accumulation of abnormal metabolites in the tissues. The presence of abnormal metabolites in the urine of mentally retarded individuals has been used worldwide for detection of inborn errors of metabolism. The purpose of the study is to determine the prevalence of inborn error of metabolism in mentally retarded children.Methods: Random urine samples were collected from mentally retarded children at two institutes in Kathmandu, and also from 60 normal children from Duwakot, Nepal after obtaining consent from their parents. Urine was then tested for the presence of amino acids, keto-acids, mucopolysaccharides, fructose, glucose and protein using simple qualitative color reactions in the laboratory.
Results:The tests detected eight cases of Phenylketonuria, which turned out to be false positive on paper chromatography. Three cases of presence of ketone bodies (acetoacetate), ten cases of α-ketoaciduria, two cases of mucopolysaccharidosis and twelve cases of...