title: High-resolution melting analysis of the common c.1905+1G>A mutation causing dihydropyrimidine dehydrogenase deficiency and lethal 5-fluorouracil toxicity.
abstract: Dihydropyrimidine dehydrogenase (DPD) deficiency is a pharmacogenetic syndrome associated with life-threatening toxicity following exposure to the fluoropyrimidine drugs 5-fluorouracil (5-FU) and capecitabine (CAP), widely used for the treatment of colorectal cancer and other solid tumors. The most prominent loss-of-function allele of the DPYD gene is the splice-site mutation c.1905+1G>A. In this study we report the case of a 73-year old woman with metastatic colorectal cancer who died from drug-induced toxicity after the first cycle of 5-FU-containing chemotherapy. Her symptoms included severe neutropenia, thrombocytopenia, mucositis and diarrhea; she died 16 days later despite intensive care measures. Post-mortem genetic analysis revealed that the patient was homozygous for the c.1905+1G>A deleterious allele and several family members consented to being screened for this mutation. This is the first report in Spain of a case of 5-FU-induced lethal toxicity associated with a genetic defect that results in the complete loss of the DPD enzyme. Although the frequency of c.1905+1G>A carriers in the white population ranges between 1 and 2%, the few data available for the Spanish population and the severity of this case prompted us to design a genotyping procedure to prevent future toxic effects of 5-FU/CAP. Since our group had previously developed a high-resolution melting (HRM) assay for the simultaneous detection of KRAS, BRAF, and/or EGFR somatic mutations in colorectal and lung cancer patients considered for EGFR-targeted therapies, we included the DPYD c.1905+1G>A mutation in the screening test that we describe herein. HRM provides a rapid, sensitive, and inexpensive method that can be easily implemented in diagnostic settings for the routine pre-therapeutic testing of a gene mutation panel with implications in the pharmacologic treatment.
authors: Molecular Genetics Unit, Hospital de Terrassa Terrassa, Spain.
authors: Emma
authors: E
authors: Borràs
authors: Emma
authors: E
authors: Dotor
authors: Angels
authors: A
authors: Arcusa
authors: Maria J
authors: MJ
authors: Gamundi
authors: Imma
authors: I
authors: Hernan
authors: Miguel
authors: M
authors: de Sousa Dias
authors: Begoña
authors: B
authors: Mañé
authors: José A G
authors: JA
authors: Agúndez
authors: Miguel
authors: M
authors: Blanca
authors: Miguel
authors: M
authors: Carballo
keywords: 5-FU; 5-fluorouracil; DPD; DPYD; HRM; capecitabine; dihydropyrimidine dehydrogenase; toxicity