phenylalanine hydroxylase deficiency

phenylalanine hydroxylase deficiency The inherited inability to normally process the amino acid phenylalanine, due to partial or complete deficiency of the enzyme phenylalanine hydroxylase. This deficiency is caused by mutation in the PAH gene on chromosome 12. Phenylalanine hydroxylase deficiency causes a spectrum of disorders, including classic phenylketonuria (PKU), variant PKU, and nonPKU elevation of phenylalanine in the blood (nonPKU HPA). See also PKU; PKU, maternal.