Inborn errors of Amino acid metabolism can manifest at any time but become most evident in infancy and early childhood. Specific symptoms depend on the type of disorder. Affected patients may have failure to thrive, neurological symptoms, digestive problems and locomotor retardation. If not diagnosed and treated promptly they can result in poor growth, developmental delays, mental retardation and death. CSF specimens are highly informative for conditions like Non-ketotic hyperglycemia and Serine biosynthesis defects.