Which enzyme deficiency is responsible for the development of phenylketonuria, a genetic disorder characterized by an inability to metabolize phenylalanine?

A Phenylalanine hydroxylase ✓
B Tyrosinase
C Homogentisate oxidase
D Cystathionine beta-synthase

Explanation

Phenylalanine hydroxylase is the enzyme responsible for converting phenylalanine to tyrosine. A deficiency in this enzyme leads to the accumulation of phenylalanine, causing phenylketonuria.

Source

Guyton and Hall Textbook of Medical Physiology
Enzymes in Disease Genetics Inborn Errors of Metabolism Hard MEDICAL Confidence: high