Three different polymorphisms of the DPYD gene associated with severe toxicity following administration of 5-FU: a case report

Background Dihydropyrimidine dehydrogenase deficiency secondary to polymorphisms in the DPYD gene can lead to significant toxicity associated with the administration of fluoropyrimidine chemotherapy. Case presentation We report a case of a 59-year-old Lebanese woman with metastatic pancreatic cancer who received FOLFIRINOX therapy and developed severe 5-fluorouracil toxicity after a single cycle. The entire DPYD gene was sequenced, and the patient was found to be heterozygous for three different polymorphisms that have reportedly been associated with dihydropyrimidine dehydrogenase deficiency. Conclusion Because data regarding the prevalence and clinical significance of several heterozygous polymorphisms in a single DPYD gene are very limited, we suggest that full gene sequencing should be carried out, at least in populations in which the allele frequencies are unknown.