What causes Dihydropyrimidine dehydrogenase deficiency ?
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. Uracil and thymine are building blocks of DNA, RNA, and molecules that serve as energy sources in cells. Mutations in the DPYD gene result in deficiencies (to various degrees) of functional DPD, interfering with the breakdown of uracil and thymine in cells. This results in excessive amounts of uracil and thymine in the blood, urine, and the fluid that surrounds the brain and spinal cord. It is currently poorly understood exactly how this cascade of events causes the signs and symptoms of the condition.