CYP3A5 phenotype-genotype correlations in a British population.
OBJECTIVE
To develop a polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP)-based assay to genotype for hepatic CYP3A5 expression and to use this assay to study a British population.


METHODS
CYP3A5-specific primers were designed with one including a base-pair mismatch to create a RsaI site in samples positive for G6986 (CYP3A5*3 allele) [correction]. Following PCR and RsaI digestion, different band patterns on electrophoresis were predicted for individuals positive for CYP3A5 (CYP3A5*1 allele) compared with those who do not express the gene (CYP3A5*3 homozygotes). The assay was validated by DNA sequencing. DNA samples from a human liver bank consisting of 22 livers whose CYP3A5 expression had been determined by immunoblotting and a group of random individuals (n = 100) from the North-east of England were genotyped by the new assay.


RESULTS
In the liver bank, five out of 22 samples expressed CYP3A5 at significant levels (>20 pmol mg-1 protein) and were found to have the genotype CYP3A5*1/CYP3A5*3 by the PCR-RFLP assay. All other liver DNA samples were CYP3A5*3 homozygotes. In the group of 100 random individuals, 13 had the genotype CYP3A5*1/CYP3A5*3 and all others were CYP3A5*3 homozygotes, predicting that 13% (95% confidence interval (CI) 6%, 20%) would show significant hepatic CYP3A5 expression. The frequency for the CYP3A5*1 allele was 0.065 (95% CI 0.032, 0.097).


CONCLUSIONS
We have developed a simple assay for the detection of the CYP3A5*1/CYP3A5*3 alleles and shown that in a British population their frequency is similar to that reported previously. We have also shown a good correlation between hepatic CYP3A5 expression and genotype for a British Caucasian liver bank.
King
Barry P
BP
Department of Pharmacological Sciences, University of Newcastle upon Tyne, Newcastle upon Tyne, UK.
Leathart
Julian B S
JB
Mutch
Elaine
E
Williams
Faith M
FM
Daly
Ann K
AK
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D004247:DNA / Q000235:genetics; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D008862:Microsomes, Liver; D008875:Middle Aged; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000379:methods*; D012150:Polymorphism, Restriction Fragment Length
D004247:DNA; D003577:Cytochrome P-450 Enzyme System; C104464:CYP3A protein, human; C510164:CYP3A5 protein, human; D051544:Cytochrome P-450 CYP3A