title: Genotyping cytochrome P450 3A5 using the Light Cycler.
abstract: Cytochrome P450 3A5 (CYP3A5) is involved in the biotransformation of many orally administered drugs, some of which are dose optimized using therapeutic drug monitoring. The CYP3A5 gene exhibits variable inter-individual expression, which is related to a single-nucleotide polymorphism. Producers of the enzyme possess at least one CYP3A5*1 allele. Knowledge of patients' CYP3A5 genotype, in conjunction with therapeutic drug monitoring (TDM), may aid patient management. Real-time polymerase chain reaction (PCR) was used to genotype the A6986G mutation of the CYP3A5 gene. Specific primers were employed to generate a DNA product, co-amplified with two internal hybridization probes, using a LightCycler. DNA melt curve analysis readily identified the genotypes CYP3A5*1/*1, CYP3A5*1/*3 and CYP3A5*3/*3. Results were confirmed using DNA sequencing with 100% correlation. Genotypes were determined from 263 individuals and compared with the genotypes of a pseudogene CYP3AP1, which is in disequilibrium with CYP3A5. This is a rapid and reliable method for genotyping the CYP3A5 polymorphism which may be used as an important adjunct to the TDM service offered by laboratories to optimize drug prescription.
authors.affiliation: Analytical Unit, Cardiac and Vascular Sciences, St George's Hospital Medical School, St George's University of London, Cranmer Terrace, London SW17 0RE, UK. frederic@sgul.ac.uk
authors.forename: Salim
authors.initials: S
authors.lastname: Fredericks
authors.forename: Michelle
authors.initials: M
authors.lastname: Moreton
authors.forename: Iain A M
authors.initials: IA
authors.lastname: MacPhee
authors.forename: Maha
authors.initials: M
authors.lastname: Mohamed
authors.forename: Sharon
authors.initials: S
authors.lastname: Marlowe
authors.forename: AnaMaria
authors.initials: A
authors.lastname: Jorga
authors.forename: Atholl
authors.initials: A
authors.lastname: Johnston
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Carter
authors.forename: David W
authors.initials: DW
authors.lastname: Holt
mesh_terms: D001483:Base Sequence; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D017931:DNA Primers; D016903:Drug Monitoring / Q000379:methods; D005838:Genotype; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*
chemical_list: D017931:DNA Primers; D003577:Cytochrome P-450 Enzyme System; C104464:CYP3A protein, human; C510164:CYP3A5 protein, human; D051544:Cytochrome P-450 CYP3A