Final answer:
Phenylketonuria (PKU) is a genetic disorder where individuals lack the enzyme phenylalanine hydroxylase. Elevated phenylalanine levels can lead to various symptoms such as delayed neurological development and mental retar_dation. The condition is inherited in a recessive manner.
Step-by-step explanation:
Phenylketonuria (PKU) is a genetic disorder where individuals lack the enzyme phenylalanine hydroxylase which is responsible for converting phenylalanine into tyrosine. Without this enzyme, phenylalanine levels rise to toxic levels and can lead to various symptoms such as delayed neurological development, hyperactivity, seizures, and mental retar_dation. The condition is inherited in a recessive manner, meaning that both parents must have at least one copy of the recessive allele to produce a child with PKU.