Phenylketonuria - Part I

Abstract
Phenylketonuria (PKU) is an inborn disorder of metabolism, caused by deficient or inactive enzyme, phenylalanine hydroxylase. Normally, phenylalanine hydroxylase breaks down one of the essential amino acids, phenylalanine, which is found in most protein-containing foods: eggs, milk, meats, and nuts. Phenylalanine hydroxylase converts phenylalanine to tyrosine, another essential amino acid, which serves as the precursor to many hormones and neurotransmitters. If phenylalanine is not metabolized, it accumulates in the tissues and exerts toxic effects on nervous and cardiovascular systems. High phenylalanine levels are particularly toxic to the brain. If untreated, affected infants frequently suffer from developmental delays, seizures and autism. Skin is often affected as well, and many individuals with phenylketonuria have eczema and scleroderma-like syndromes. In addition, dilution of the skin and hair pigment have been observed in such individuals, as tyrosine is a precursor to melanin, the skin pigment. .

Phenylketonuria is an autosomal recessive disorder, which results from a mutation in the gene that codes for an enzyme, phenylalanine hydroxylase. This gene is located on chromosome 12.

Read full article for:

• Genetics of Phenylketonuria
• Incidence rates
• Treatment options