The genetic disease phenylketonuria (PKU) involves an interplay between which two factors?

• A. Genetics, environment
• B. Genetics, mutations
• C. Environment, lifestyle
• D. Genetics, diet

Answer: (A)

Phenylketonuria (PKU) is a classic example of a genetic disorder that results from a genetic mutation that affects the metabolism of phenylalanine, an amino acid. The underlying cause of PKU is a mutation in the gene that encodes the enzyme phenylalanine hydroxylase, which is essential for converting phenylalanine into tyrosine. This results in the accumulation of phenylalanine to toxic levels in the body if not managed properly.

The role of the environment, particularly diet, is crucial in the management of PKU. Individuals with this condition must adhere to a strict low-phenylalanine diet to prevent intellectual disability and other neurological issues associated with the disease. This interplay between the genetic predisposition to accumulate phenylalanine and environmental factors, specifically dietary intake, emphasizes the concept of gene-environment interaction in the manifestation of PKU.

Therefore, the correct response emphasizes the importance of both genetic and environmental factors in the condition, highlighting that while the genetic mutation is the foundational cause of the disease, environmental intervention through diet is essential for management and prevention of symptoms.