Lethal outcome of a patient with a complete dihydropyrimidine dehydrogenase (DPD) deficiency after administration of 5-fluorouracil: frequency of the common IVS14+1G>A mutation causing DPD deficiency.

Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme in the catabolism of 5-fluorouracil (5FU), and it is suggested that patients with a partial deficiency of this enzyme are at risk from developing a severe 5FU-associated toxicity. In this study, we demonstrated that a lethal toxicity after a treatment with 5FU was attributable to a complete deficiency of DPD. Analysis of the DPD gene for the presence of mutations showed that the patient was homozygous for a G-->A mutation in the invariant GT splice donor site flanking exon 14 (IVS14+1G>A). As a consequence, no significant residual activity of DPD was detected in peripheral blood mononuclear cells. To determine the frequency of the IVS14+1G>A mutation in the Dutch population, we developed a novel PCR-based method allowing the rapid analysis of the IVS14+1G>A mutation by RFLP. Screening for the presence of this mutation in 1357 Caucasians showed an allele frequency of 0.91%. In our view, the apparently high prevalence of the IVS14+1G>A mutation in the normal population, with 1.8% heterozygotes, warrants genetic screening for the presence of this mutation in cancer patients before the administration of 5FU.

Clinical implications of dihydropyrimidine dehydrogenase (DPD) deficiency in patients with severe 5-fluorouracil-associated toxicity: identification of new mutations in the DPD gene.

Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme in the catabolism of 5-fluorouracil (5FU), and it is suggested that patients with a partial deficiency of this enzyme are at risk for developing a severe 5FU-associated toxicity. To evaluate the importance of this specific type of inborn error of pyrimidine metabolism in the etiology of 5FU toxicity, an analysis of the DPD activity, the DPD gene, and the clinical presentation of patients suffering from severe toxicity after the administration of 5FU was performed. Our study demonstrated that in 59% of the cases, a decreased DPD activity could be detected in peripheral blood mononuclear cells. It was observed that 55% of patients with a decreased DPD activity suffered from grade IV neutropenia compared with 13% of patients with a normal DPD activity (P = 0.01). Furthermore, the onset of toxicity occurred, on average, twice as fast in patients with low DPD activity as compared with patients with a normal DPD activity (10.0 +/- 7.6 versus 19.1 +/- 15.3 days; P < 0.05). Analysis of the DPD gene of 14 patients with a reduced DPD activity revealed the presence of mutations in 11 of 14 patients, with the splice site mutation IVS14+1G-->A being the most abundant one (6 of 14 patients; 43%). Two novel missense mutations 496A-->G (M166V) and 2846A-->T (D949V) were detected in exon 6 and exon 22, respectively. Our results demonstrated that at least 57% (8 of 14) of the patients with a reduced DPD activity have a molecular basis for their deficient phenotype.

Specific translocation t(1;3) in acute myelomonocytic leukemia: a further case.

We describe herein a translocation, t(1;3)(p36;q21), that was found in the bone marrow of a patient with acute myelomonocytic leukemia preceded by a long lasting myelodysplastic phase. An identical translocation has been reported in three other myelodysplastic patients. one of whom also developed an acute myelomonocytic leukemia. The possible significance of this specific translocation is briefly discussed.

Limbic encephalitis. A rare presentation of the small-cell lung carcinoma.

Two patients with an acute organic brain syndrome and accompanying neurological symptoms are described. Extensive work up showed that both patients suffered from small-cell lung cancer. Cerebral metastases were absent. Following chemotherapy and radiotherapy to the primary tumor one of the two patients showed a complete remission of psychiatric symptoms for one year. A paraneoplastic origin of this syndrome, in the literature known as limbic encephalitis, is postulated. The exact cause of this syndrome is yet unknown. Recent research reveals data indicating an immunological pathogenesis. The major clinical importance of this (neuro)-psychiatric syndrome is that its appearance may serve as a warning sign for an occult malignancy; furthermore, effective treatment of the primary malignancy can reverse the encephalitis. Thus antitumor therapy can result in a prolonged survival and considerably improved quality of life.

Sarcoid-like lymphadenopathy mimicking metastatic testicular cancer.

A case of nonseminomatous testicular cancer and enlarged mediastinal lymph nodes, which were interpreted as metastases, is reported. When there was no change after two courses of chemotherapy, a mediastinoscopy was performed and the results showed sarcoidosis.

Reduced 5-FU clearance in a patient with low DPD activity due to heterozygosity for a mutant allele of the DPYD gene.

5-fluorouracil pharmacokinetics, dihydropyrimidine dehydrogenase-activity and DNA sequence analysis were compared between a patient with extreme 5-fluorouracil induced toxicity and six control patients with normal 5-fluorouracil related symptoms. Patients were treated for colorectal cancer and received chemotherapy consisting of leucovorin 20 mg m(-2) plus 5-fluorouracil 425 mg m(-2). Blood sampling was carried out on day 1 of the first cycle. The 5-fluorouracil area under the curve(0-->3h) in the index patient was 24.1 mg h l(-1) compared to 9.8+/-3.6 (range 5.4-15.3) mg h l(-1) in control patients. The 5-fluorouracil clearance was 520 ml min(-1) vs 1293+/-302 (range 980-1780) ml min(-1) in controls. The activity of dihydropyrimidine dehydrogenase in mononuclear cells was lower in the index patient (5.5 nmol mg h(-1)) compared to the six controls (10.3+/-1.6, range 8.0-11.7 nmol mg h(-1)). Sequence analysis of the dihydropyrimidine dehydrogenase gene revealed that the index patient was heterozygous for a IVS14+1G>A point mutation. Our results indicate that the inactivation of one dihydropyrimidine dehydrogenase allele can result in a strong reduction in 5-fluorouracil clearance, causing severe 5-fluorouracil induced toxicity.