a. “Phenylketonura, or PKU, is an inborn error of metabolism characterized by the inability of the body to convert the essential amino acid phenylalanine to tyrosine” (Huether 416). PKU has an occurrence rate in the U.S. of 1:15,000. It is caused by the deficiency of phenylalanine hydroxylase. This deficiency causes phenylalanine to accumulate in the serum. Phenylalanine hydroxylase monitors and controls the conversion of the amino acid into tyrosine. Tyrosine is used with the biosynthesis or proteins, thyroxin, melanin, and catecholamines in the adrenal medulla and brain. There are however, different types of PKU. Some involve impairing the synthesis of cofactors which cause the elevation of phenylalanine levels. When these levels are
