phenylketonuria (redirected from hyperphenylalaninemia)

phenylketonuria (fĕn'əlkēt'ənr`ēə) (PKU), inherited metabolic disorder caused by the absence of a specific enzyme (phenylalanine hydroxylase). The absence of this enzyme, a recessive trait, prevents the body from making use of phenylalanine, one of the amino acids in most protein-rich foods, and almost always leads to mental retardation and schizoid changes; convulsions also commonly occur. Early diagnosis and treatment, which includes a carefully regulated low-phenylalanine diet begun during the first few weeks of life, may prevent serious mental deficiency. Positive improvement has been seen even when therapy is started in well-established cases. Most states have made the PKU blood or urine test mandatory for all newborn infants.

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phenylketonuria (PKU)

 or phenylpyruvic oligophrenia

Inability to normally metabolize phenylalanine, the accumulation of which interferes with normal childhood development. Central nervous system effects include intellectual disability and seizures (see epilepsy), with behavioral signs seen at four to six months of age. Abnormal metabolism also leads to low melanin levels, with light hair, eye, and skin colour. Tests detect this recessive genetic disorder (see congenital disorder; recessiveness) in two-thirds of the 1 in 10,000 newborns born with high levels of phenylalanine. Keeping phenylalanine out of the diet (by total avoidance of meat, dairy, and high-protein foods and aspartame) until adolescence permits normal development. Protein is supplied in a phenylalanine-free formula. Pregnant women with PKU must resume the diet to prevent severe damage to the unborn child.