DPD deficiency
| Dihydropyrimidine dehydrogenase deficiency | |
|---|---|
| Classification and external resources | |
| OMIM | 274270 |
| DiseasesDB | 29817 |
| MeSH | D054067 |
Dihydropyrimidine dehydrogenase deficiency (DPD deficiency) is an autosomal recessivemetabolic disorder in which there is absent or significantly decreased activity of dihydropyrimidine dehydrogenase, an enzyme involved in the metabolism of uracil and thymine.
Individuals with this condition may develop life-threatening toxicity following exposure to 5-fluorouracil (5-FU), a chemotherapy drug that is used in the treatment of cancer. Beside 5-FU, widely prescribed oral fluoropyrimidine capecitabine (Xeloda) could put DPD-deficient patients at risk of experiencing severe or lethal toxicities as well.
DPD deficiency is inherited in an autosomal recessive manner. This means the defective gene responsible for the disorder is located on an autosome, and two copies of the defective gene (one inherited from each parent) are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene, but usually do not experience any signs or symptoms of the disorder.
Current research suggests that nearly 8% of the population has at least partial DPD deficiency. A diagnostics determination test for DPD deficiency is available and it is expected that with a potential 500,000 people in North America using 5-FU this form of testing will increase. The whole genetic events affecting the DPYD gene and possibly impacting on its function are far from being elucidated, and epigenetic regulations could probably play a major role in DPD deficiency. It seems that the actual incidence of DPD deficiency remains to be understood because it could depend on the very technique used to detect it. Screening for genetic polymorphisms affecting the DPYD gene usually identify less than 5% of patients bearing critical mutations, whereas functional studies suggest that up to 20% of patients could actually show various levels of DPD deficiency.
Women could be more at risk than men. It is more common among African-Americans than it is among Caucasians.
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