Which enzyme is involved in the conversion of phenylalanine to tyrosine, and its deficiency leads to phenylketonuria?

A Phenylalanine hydroxylase ✓
B Tyrosinase
C Dihydropteridine reductase
D Homogentisate 1,2-dioxygenase

Explanation

Phenylalanine hydroxylase is the enzyme responsible for converting phenylalanine to tyrosine, and its deficiency leads to the accumulation of phenylalanine, causing phenylketonuria.

Source

Nelson's Textbook of Pediatrics
Enzymes in Disease Biochemistry Amino Acid Metabolism Disorders Hard MEDICAL Confidence: high