Question

Phenylketonuria is caused by:

• A. Tyrosine hydroxylase
• B. Phenylalanine hydroxylase (PAH)
• C. Methionine synthase
• D. Argininosuccinate lyase

Hint:

Phenylketonuria is an autosomal recessive disorder detected through newborn screening. Early dietary management can prevent its adverse effects.

Answer 1

The Correct Option is B

Phenylketonuria (PKU) is a genetic disorder caused by a deficiency of the enzyme phenylalanine hydroxylase (PAH). 

This enzyme is responsible for converting the amino acid phenylalanine into tyrosine. Without functional PAH: Phenylalanine accumulates in the body, leading to toxic levels. This causes severe intellectual disabilities, delayed development, and other neurological problems if untreated. PKU is typically managed through a diet low in phenylalanine.