Identification of a novel mutation in the dihydropyrimidine dehydrogenase gene in a patient with a lethal outcome following 5-fluorouracil administration and the determination of its frequency in a population of 500 patients with colorectal carcinoma.
OBJECTIVE
Life-threatening toxic side-effects following 5-FU exposure have been related to deficiency of dihydropyrimidine dehydrogenase (DPD), the rate-limiting enzyme in its catabolism. We presently report a new DPYD gene SNP in a Spanish woman who died from multivisceral 5-FU-induced toxicity.


METHODS
We looked for 22 known SNPs by Pyrosequecing. Then, we sequenced the whole 23 exons of DPYD, along with adjacent intronic sequences. PCR was carried out to determine whether or not exons were deleted in the DPYD. To determine whether the predicted stop codon indeed resulted in a truncated protein, a bacterial expression vector was employed to generate the predicted protein. 500 patients were genotyped to determine allele frequency.


RESULTS
A novel mutation 464 T>A was identified in DPYD gene exon 5, resulting in the replacement of leucine 155 by a stop codon in the protein. We confirmed this mutation by Pyrosequencing and its involvement by a protein truncation test. We genotyped the patient's family and the allele frequency was 0.2%.


CONCLUSIONS
The involvement of this variant in 5-FU life-threatening toxicity supports its inclusion in pretherapeutic genetic screening.
Morel
A
A
Department of Oncopharmacology and Pharmacogenetics, INSERM U564, Anti Cancer Centre Paul Papin, 2 rue Moll, 49933 Angers cedex 09, France. a.morel@unimedia.fr
Boisdron-Celle
M
M
Fey
L
L
Lainé-Cessac
P
P
Gamelin
E
E
D000225:Adenine; D000368:Aged; D000483:Alleles; D015179:Colorectal Neoplasms / Q000235:genetics*; D004252:DNA Mutational Analysis; D018076:DNA, Complementary / Q000235:genetics; D042943:Dihydrouracil Dehydrogenase (NADP) / Q000235:genetics*; D005091:Exons / Q000235:genetics; D017809:Fatal Outcome; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage* / Q000097:blood / Q000494:pharmacology*; D005787:Gene Frequency; D006801:Humans; D007438:Introns / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D010375:Pedigree; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013941:Thymine; D014498:Uracil / Q000031:analogs & derivatives / Q000097:blood
D018076:DNA, Complementary; C007419:dihydrouracil; D014498:Uracil; D042943:Dihydrouracil Dehydrogenase (NADP); D000225:Adenine; D013941:Thymine; D005472:Fluorouracil