Final answer:
Phenylketonuria (PKU) is a genetic disorder caused by mutations that impact the enzyme necessary for metabolizing the amino acid phenylalanine, leading to serious health problems if not managed with a strict diet.
Step-by-step explanation:
Phenylketonuria (PKU) is classified as a genetic disorder, not a congenital anomaly. It results from mutations in the genetic material, specifically a loss of function in the enzyme phenylalanine hydroxylase, which is necessary for the metabolism of the amino acid phenylalanine into tyrosine.
Without this enzyme, phenylalanine accumulates to toxic levels, leading to damage to the central nervous system and other serious health issues. Following a strict diet low in phenylalanine from childhood can significantly reduce the impact of symptoms.