A person with PKU controls the buildup of phenylpyruvic acid in his or her blood by restricting dietary intake of phenylalanine, thus avoiding the severe symptoms of mental retardation, slow growth rate, and early death

Yet he or she still exhibits the symptoms of fair skin and low adrenaline levels. Why?


The PKU mutation is in the gene for phenylalanine hydroxylase, the enzyme that converts phenylalanine to tyrosine. Tyrosine is essential for melanin and adrenaline production. A PKU individual cannot make tyrosine, and it is difficult to obtain enough tyrosine from food intake to avoid any symptoms of the disease.

Biology & Microbiology

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