Which enzyme deficiency is responsible for the development of phenylketonuria?

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

Explanation

Phenylketonuria is a genetic disorder caused by a deficiency of the enzyme phenylalanine hydroxylase, which is necessary for the conversion of phenylalanine to tyrosine. This deficiency leads to the accumulation of phenylalanine in the body, causing intellectual disability and other symptoms.

Source

Scriver's The Metabolic and Molecular Bases of Inherited Disease
Enzymes in Disease Genetics and Metabolism Inborn Errors of Metabolism Hard MEDICAL Confidence: high