Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) sepiapterin reductase deficiency ?
    ### Response:
    Sepiapterin reductase deficiency is a condition characterized by movement problems, most often a pattern of involuntary, sustained muscle contractions known as dystonia. Other movement problems can include muscle stiffness (spasticity), tremors, problems with coordination and balance (ataxia), and involuntary jerking movements (chorea).
    