Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Dihydropyrimidine dehydrogenase deficiency ?
    ### Response:
    What causes dihydropyrimidine dehydrogenase (DPD) deficiency? DPD deficiency is caused by mutations in the DPYD gene. This gene provides instructions for making an enzyme called dihydropyrimidine dehydrogenase (DPD), which is involved in the breakdown of molecules called uracil and thymine.
    