Phenylketonuria

Phenylketonuria (PKU) is a rare, inborn metabolism error resulting from a deficiency of phenylalanine hydroxylase (an enzyme) transmitted by an autosomal (i.e., nonsex chromosome) recessive gene. The incidence of PKU in the United States is approximately 1:15,000, and 1 in 60 persons (generally mothers) is a carrier of the gene.

The most serious outcomes of PKU are moderate to severe mental retardation and behaviors such as hyperactivity, inattention, perceptual–motor problems, aggressiveness, negative mood, and motor difficulties. Children untreated for PKU are normal at birth, but begin to show slowed brain development by four months.

Well-established screening procedures (via blood analysis) are used to test every child for PKU at birth. Managing the disorder via dietary supplements from the first month of life can result in normal development. ...