الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 200 |  |  |
| | | from | 200 | | |
Abstract
Disorders of amino acid and organic acid metabolism collectively represent a group of over 70 inherited diseases that are most frequently encountered in the neonatal period. Disorders of amino acid metabolism are caused by enzyme deficiencies resulting in the accumulation of metabolites to levels which cause organ damage. The brain, liver and kidneys are the most frequently affected organs Symptoms may be acutely present or become apparent weeks or months after birth as a result of the cumulative effect of damage. Neonates presenting with acute metabolic distress caused by aminoorganic acidopathies can be assigned to one of the following groups: (1) Neurological distress with hyperammonemia. (2)Neurological distress with ketosis and hyperammonemia. (3) Neurological distress without metabolic decompensation. (4) Hepatic failure syndrome. Many procedures are available for measuring amino acids in biological samples. Three groups of tests for amino acids analysis are of importance: (1) Screening tests, including TLC, urine color test, and the Guthrie microbiological test. (2) Quantitative tests for monitoring treatment or confirming an initial diagnosis. Ion exchange chromatography or HPLC are widely used for this purpose. Some individual amino acids may also be determined by quantitative chemical methods. (3) Exact identification of unknown amino acid or metabolite. Because chromatographic separation gives only the retention time as an identifing charecteristic, other properties such as the infrared spectrum may need to be examined; discriminating automated methods include GC/MS and MS/MS. Neonatal screening includes; prenatal screening and postnatal diagnosis. The prenatal screening involves methods of aminocentesis, gene analysis by biopsy of trophoblastic villi and DNA technique. Postnatal Screening of Aminoacidopathies may be mandatory screening like PKU in USA; or non mandatory (selective screening) which be initiated when the possibility is considered, the latter occur in non developed countries.