title: Genotype relationships in the CYP3A locus in Caucasians.
abstract: Genetic polymorphisms of the human CYP3A family affect clinical drug efficacy and may modify cancer risk. CYP3A genes show high sequence similarity that had previously lead to misallocation of CYP3A polymorphisms. Recent studies indicated a high degree of or even complete linkage for certain CYP3A alleles. Reliable LightCycler-based genotyping methods were developed and their degree of linkage in a large Caucasian population (n = 1210) investigated. Strong linkage disequilibrium was confirmed between CYP3A4, CYP3A5, and CYP3AP1 (each at P < 10(-5)). Contrary to some previous results claiming complete linkage between the phenotypically relevant CYP3A5*1 and a variant in a pseudogene promoter region CYP3AP1*1 we found among 428 controls (15 of 66) and 782 lung cancer cases (25 of 115) approximately 22% of CYP3AP1*1 carriers to be homozygous for CYP3A5*3 We conclude that contrary to previous assumptions, the CYP3AP1 genotype is not a reliable predictor for CYP3A5 activity.
authors.affiliation: Deutsches Krebsforschungszentrum, Abteilung Toxikologie und Krebsrisikofaktoren, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany. h.dally@dkfz.de
authors.forename: Heike
authors.initials: H
authors.lastname: Dally
authors.forename: Helmut
authors.initials: H
authors.lastname: Bartsch
authors.forename: Birgit
authors.initials: B
authors.lastname: Jäger
authors.forename: Lutz
authors.initials: L
authors.lastname: Edler
authors.forename: Peter
authors.initials: P
authors.lastname: Schmezer
authors.forename: Bertold
authors.initials: B
authors.lastname: Spiegelhalder
authors.forename: Hendrik
authors.initials: H
authors.lastname: Dienemann
authors.forename: Peter
authors.initials: P
authors.lastname: Drings
authors.forename: Klaus
authors.initials: K
authors.lastname: Kayser
authors.forename: Volker
authors.initials: V
authors.lastname: Schulz
authors.forename: Angela
authors.initials: A
authors.lastname: Risch
mesh_terms: D000483:Alleles; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics; D004247:DNA / Q000737:chemistry; D008040:Genetic Linkage; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D015810:Linkage Disequilibrium; D010089:Oxidoreductases, N-Demethylating / Q000235:genetics*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011544:Pseudogenes; D044465:White People
chemical_list: D004247:DNA; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C104464:CYP3A protein, human; C510164:CYP3A5 protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D010089:Oxidoreductases, N-Demethylating