Describe phenylketonuria (PKU). Explain how it occurs and how it is treated

Question

What will be an ideal response?

Answer 1

Answer: Phenylketonuria, or PKU, is one of the most frequently occurring recessive disorders. It affects the way the body breaks down proteins contained in many foods. Infants born with two recessive alleles lack an enzyme that converts one of the basic amino acids that make up proteins (phenylalanine) into a byproduct essential for body functioning (tyrosine). Without this enzyme, phenylalanine quickly builds to toxic levels that damage the central nervous system. By age 1, infants with PKU suffer from permanent intellectual disability.
All U.S. states require that each newborn be given a blood test for PKU. If the disease is found, doctors place the baby on a diet low in phenylalanine. Children who receive this treatment nevertheless show mild deficits in certain cognitive skills, such as memory, planning, decision making, and problem solving, because even small amounts of phenylalanine interfere with brain functioning. But as long as dietary treatment begins early and continues, children with PKU usually attain an average level of intelligence and have a normal lifespan.