Final answer:
Phenylketonuria (PKU) is caused by an inherited deficiency of the enzyme phenylalanine hydroxylase, leading to toxic accumulation of phenylalanine which affects the central nervous system and brain.
Step-by-step explanation:
Phenylketonuria (PKU) is a genetic disorder caused by an inherited lack of an enzyme. Specifically, individuals with PKU have insufficient activity of the enzyme phenylalanine hydroxylase. This enzyme is crucial for converting the amino acid phenylalanine into tyrosine. Without proper function of this enzyme, phenylalanine accumulates in the body to toxic levels, leading to damage to the central nervous system and brain. Symptoms of PKU can include delayed neurological development, intellectual disability, seizures, skin rashes, tremors, and uncontrolled movements. PKU can also pose a high risk during pregnancy, as excessive phenylalanine can cross the placenta and affect fetal development, resulting in heart defects and intellectual disability. Early diagnosis and management with a strict diet low in phenylalanine are essential to prevent the severe consequences of this disorder.