This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Phenylalanine and Tyrosine metabolism Detail, Subject name: Biochemistry
Nitisinone is an example of 
Select and explain. 
A. Enzyme activation therapy, B. Enzyme replacement therapy, C. Substrate addition therapy, D. Substrate reduction therapy
D: Substrate reduction therapy
Answer: D: Substrate reduction therapy 
Explanation: Nitisinone is prescribed for infantile tyrosinemia because it decreases production of the substrate (fumarylacetoacetate) for the hydrolase, thus decreasing the velocity of the reaction preventing substrate accumulation.