Definition and epidemiology Inherited disorders of amino acid, organic acid, and peroxisomal metabolism are individually rare but have a high cumulative frequency. The underlying biochemical defect is heterogeneous. Neurological manifestations are common. Epilepsy can be observed during the course of many disorders, usually as part of a larger clinical spectrum. Deficiencies of enzymes involved in amino acid catabolism of phenylalanine or glycine frequently result in the accumulation of toxic substances and these “catabolic” aminoacidopathies are known to be responsible for brain damage with mental retardation and seizures. Phenylketonuria was one of the first neurogenetic disorders to be identified (by Folling in 1934) and the first inborn error of metabolism to be treated successfully with diet (Bickel 1953). In the 1960s, neonatal screening was introduced for the diagnosis of phenylketonuria (Guthrie and Susi 1963) and later extended to several other disorders (Scriver et al. 2001). At the moment, in many countries, phenylketonuria and hyperphenylalaninemias are recognized by newborn screening with Guthrie test or tandem mass spectroscopy (LC-MS/MS) and therapy can begin in the neonatal period to prevent chronic neurological damage. Neonatal screening by LC-MS/MS, recently introduced in some countries, allows the diagnosis of many disorders of intermediary metabolism (aminoacidopathies, organic acidurias, fatty acid oxidation disorders, and some urea cycle defects). Non-ketotic hyperglycinemia is the most common amino acid disorder causing epilepsy in countries in which phenylketonuria is detected by newborn screening (Fernandes et al. 2000; Scriver et al. 2001).
|Title of host publication||The Causes of Epilepsy: Common and Uncommon Causes in Adults and Children|
|Publisher||Cambridge University Press|
|Number of pages||15|
|ISBN (Print)||9780511921001, 9780521114479|
|Publication status||Published - Jan 1 2011|
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