Hair is pale and brown

In patients with phenylketonuria, because tyrosinase is inhibited, melanin synthesis is reduced, so the child's hair is pale and brown. Phenylketonuria (PKU) is a genetic disease caused by phenylalanine hydroxylase (PAH) deficiency or decreased activity in the liver, resulting in phenylalanine metabolism disorders. It is more common in hereditary disorders of amino acid metabolism.