PURPOSE: Deficiency of dihydropyrimidine dehydrogenase (DPD) has been associated with severe fluoropyrimidines (FP) toxicity. Mutations in DPD-coding gene (DPYD) were shown to increase the risk of severe toxicity in FP-treated cancer patients. However, the majority of DPYD alterations characterized in these patients has been considered as polymorphisms and known deleterious mutations are rare and present in only limited subgroup of patients with high toxicity. Recently, the common fragile site FRA1E was mapped within DPYD locus but intragenic rearrangements in DPYD gene were not studied so far. METHODS: We performed the analysis of intragenic rearrangements of DPYD using multiplex ligation-dependent probe amplification in 68 patients with high-grade gastrointestinal and/or hematological toxicity developed at the beginning of FP treatment. RESULTS: We did not detect any deletion/duplication of one or more DPYD exons in analyzed patients. CONCLUSIONS: We assume that rearrangements in DPYD gene play insignificant role in the development of serious FP-related toxicity.

Institute of Biochemistry and Experimental Oncology 1st Faculty of Medicine Charles University Prague Prague 2 Czech Republic