The genetic inability to metabolize the amino acid phenylalanine is known as Phenylketonuria (PKU).

Phenylketonuria (PKU)

• Cause: It is caused by a mutation in the gene that encodes the enzyme phenylalanine hydroxylase (PAH), which is essential for converting phenylalanine into tyrosine.
• Effect: Without this enzyme, phenylalanine accumulates in the body, leading to toxic levels that can cause brain damage and intellectual disabilities if not managed.
• Inheritance: PKU is an autosomal recessive disorder, meaning a person must inherit two copies of the mutated gene (one from each parent) to develop the condition.
• Management: It is managed by a strict diet low in phenylalanine, starting in infancy, to prevent the harmful effects of the amino acid buildup.

Newborns are routinely screened for PKU as part of standard neonatal screening programs in many countries.