Amino acid disorder screening is done in newborns, and sometimes children and adults, to detect congenital errors in metabolism of amino acids. Twenty of the 100 known amino acids are the main building blocks for human proteins. Proteins regulate every aspect of cellular function. Of these 20 amino acids, ten are not made by the body and must be acquired through diet

Some congenital amino acid metabolic defects cause mental retardation that can be prevented with prompt treatment of the newborn. One of the best known examples of this is phenylketonuria (PKU). This is an genetic error in metabolism of phenylalanine, an amino acid found in milk. Individuals with PKU do not produce the enzyme necessary to break down phenylalanine. PKU occurs in about one out of 16,000 live births in the United States, but is more prevalent in Caucasians, and less prevalent...