Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to sepiapterin reductase deficiency ?
    ### Response:
    Mutations in the SPR gene cause sepiapterin reductase deficiency. The SPR gene provides instructions for making the sepiapterin reductase enzyme. This enzyme is involved in the production of a molecule called tetrahydrobiopterin (also known as BH4). Specifically, sepiapterin reductase is responsible for the last step in the production of tetrahydrobiopterin.
    