Why do people with phenylktonuria have light skin colour?

People with phenylketonuria (PKU) have a genetic deficiency in the enzyme phenylalanine hydroxylase, which leads to an inability to metabolize phenylalanine. This condition affects the production of melanin, the pigment responsible for skin, hair, and eye color. As a result, individuals with PKU often have lighter skin and hair, as they do not produce enough melanin compared to those without the condition. Additionally, the buildup of phenylalanine can disrupt other metabolic processes, further influencing pigmentation.