ABSTRACT
A practical limitation to the identification of genetic profiles predictive of drug-induced adverse events is the number of patients with the adverse event that can be tolerated before the drug is withdrawn. Whole genome screening for regions of linkage disequilibrium (LD) associated with a particular phenotype may provide the mechanism to rapidly discover specific and sensitive profiles. We have used data from a large phase III clinical trial of tranilast and typed 76 SNPs over a 2.7 megabase region flanking the uridine diphosphate glucuronosyltranserferase 1A1 gene. Three SNPs within one LD block showed strong association with tranilast-induced hyperbilirubinemia (P<10(-13)). Our data illustrated that a genome-wide LD scan of 100,000-200,000 SNPs is sufficient to identify a pharmacogenetic association with a drug-induced adverse event.
Subject(s)
Linkage Disequilibrium/genetics , Pharmacogenetics/methods , Polymorphism, Single Nucleotide/genetics , Clinical Trials, Phase III as Topic/statistics & numerical data , Glucuronosyltransferase/genetics , Humans , ortho-Aminobenzoates/therapeutic useABSTRACT
Tranilast (N-(3'4'-demethoxycinnamoyl)-anthranilic acid (N-5)) is an investigational drug for the prevention of restenosis following percutaneous transluminal coronary revascularization. An increase in bilirubin levels was observed in 12% of patients upon administration of tranilast in a phase III clinical trial. To identify the potential genetic factors that may account for the drug-induced hyperbilirubinemia, we examined polymorphisms in the uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) gene in over a thousand patients. Our results suggested that the TA repeat polymorphism in UGT1A1, which predisposes some individuals to Gilbert's syndrome, predicted the susceptibility to tranilast-induced hyperbilirubinemia. The (TA)(7)/(TA)(7) genotype was present in 39% of the 127 hyperbilirubinemic patients vs 7% of the 909 controls (P=2 x 10(-22)). Rapid identification of genetic factors accounting for the observed adverse effect during the course of a double-blind clinical trial demonstrated the potential application of pharmacogenetics in the clinical development of safe and effective medicines.
Subject(s)
Genetic Predisposition to Disease , Gilbert Disease/enzymology , Gilbert Disease/genetics , Glucuronosyltransferase/genetics , Hyperbilirubinemia/genetics , ortho-Aminobenzoates/adverse effects , Dinucleotide Repeats/genetics , Double-Blind Method , Genetic Variation , Humans , Hyperbilirubinemia/chemically induced , Isoenzymes/genetics , Polymorphism, Genetic , Prospective StudiesABSTRACT
We have identified a migraine locus on chromosome 19p13.3/2 using linkage and association analysis. We isolated 48 single-nucleotide polymorphisms within the locus, of which we genotyped 24 in a Caucasian population comprising 827 unrelated cases and 765 controls. Five single-nucleotide polymorphisms within the insulin receptor gene showed significant association with migraine. This association was independently replicated in a case-control population collected separately. We used experiments with insulin receptor RNA and protein to investigate functionality for the migraine-associated single-nucleotide polymorphisms. We suggest possible functions for the insulin receptor in migraine pathogenesis.
Subject(s)
Alleles , Migraine Disorders/genetics , Polymorphism, Single Nucleotide , Receptor, Insulin/genetics , Base Sequence , Case-Control Studies , Chromosome Mapping , Chromosomes, Artificial, Bacterial , Chromosomes, Human, Pair 19 , DNA Primers , Female , Genetic Predisposition to Disease , Genotype , Humans , Linkage Disequilibrium , Male , Protein Binding , Receptor, Insulin/metabolism , Reproducibility of Results , White People/geneticsABSTRACT
PURPOSE: Our goal is to identify the gene responsible for X-linked cone-rod dystrophy (COD1) that has been localized to a limited region of Xp11.4. METHODS: A complete physical contig of the COD1 region was partially sequenced and subjected to BLAST searches to identify homologies with GenBank ESTs. ESTs were analyzed for overlapping or related cDNA sequences and retinal expression by PCR screening of multiple human retina cDNA libraries. RACE was performed to complete the missing 5' end of the transcripts. Transcripts were compared with genomic sequences to specify intron-exon boundaries. Genomic DNAs from COD1-affected males from 3 families were screened for mutations using direct PCR sequencing of the exons. RESULTS: The vacuolar proton-ATPase membrane sector-associated protein M8-9 (APT6M8-9) gene was identified within our critical region. We confirmed its retinal expression and its genomic location in our physical contig. Eight exons (with flanking intronic sequences) were characterized from partial cDNA sequence and genomic sequence data. An additional 5' end exon was identified using RACE. No mutations were found in the COD1-affected males. CONCLUSIONS: The combination of disease mapping and information from the Human Genome project has enabled us to identify candidate genes within the COD1 region, including APT6M8-9 gene. We found no evidence that this gene is responsible for COD1 in our families, but it may be an important candidate for other diseases that have been mapped to this region of the X chromosome.
Subject(s)
ATP-Binding Cassette Transporters , Adenosine Triphosphatases/genetics , Genetic Linkage , Proton-Translocating ATPases/genetics , Retinitis Pigmentosa/genetics , Saccharomyces cerevisiae Proteins , Vacuolar Proton-Translocating ATPases , X Chromosome/genetics , Amino Acid Sequence , Base Sequence , Chromosome Mapping , Color Vision Defects/enzymology , Color Vision Defects/genetics , DNA Primers/chemistry , Exons , Gene Library , Humans , Male , Molecular Sequence Data , Mutation , Proton Pumps/genetics , Retinitis Pigmentosa/enzymology , Sequence Homology, Nucleic AcidABSTRACT
Butylated hydroxyanisole (BHA) is a commonly used food additive with demonstrated inhibitory action against chemical carcinogenesis in animals. In order to elucidate the mechanism of the anticarcinogenic action, the effects of BHA on benzo(a)pyrene (BP) metabolism were studied with lung microsomes from female mice. BHA treatment (0.5% in the diet for 7 days) inhibited BP metabolism and altered the ratios among different metabolites as analyzed by high-performance liquid chromatography. The treatment reduced the metabolic formation of 9,10-dihydroxy-9,10-dihydrobenzo(a)pyrene, but not the production of 3-hydroxybenzo(a)pyrene and trans-4,5-dihydroxy-4,5-dihydrobenzo(a)pyrene. Since the gross microsomal cytochrome P-450 content was not significantly affected by the treatment, the change of regioselectivity in BP metabolism was probably due to the alteration of cytochrome P-450 isozyme composition by dietary BHA. General and regioselective inhibition of BP metabolism was also observed when BHA was added to the lung microsomal incubation mixture. The formation of 9,10-dihydroxy-9,10-dihydrobenzo(a)pyrene and 9-hydroxybenzo-(a)pyrene was inhibited more severely than that of trans-4,5-dihydroxy-4,5-dihydrobenzo(a)pyrene and trans-7,8-dihydroxy-7,8-dihydrobenzo(a)pyrene, but the production of 3-hydroxy-benzo(a)pyrene was not inhibited. Dietary BHA treatment also decreased the microsomal metabolism of trans-7,8-dihydroxy-7,8-dihydrobenzo(a)pyrene to n-7,t-8-dihydroxy-t-9,10-oxy-7,8,9,10-tetrahydrobenzo(a)pyrene and r-7,t-8-dihydroxy-c-9,10-oxy-7,8,9,10-tetrahydrobenzo(a)pyrene. Considering that the former diol-epoxide is a suspected ultimate carcinogen, the observed inhibitions of BP metabolism in the formation of diol-epoxides may be closely related to the anticarcinogenic action of BHA.