CYP3A4-V Polymorphism Detection by PCR-Restriction Fragment Length Polymorphism Analysis and Its Allelic Frequency among 199 Dutch Caucasians

Abstract

Interindividual variation in drug metabolism is a complicating factor in pharmacotherapy. Enzymes of the cytochrome P450 system are involved in the metabolism of several endogenous substrates and a broad range of foreign compounds, such as drugs, environmental pollutants, and carcinogens (1). The cytochrome P450 enzyme family consists of several subfamilies, with CYP3A4 being the most abundant P450 enzyme in human liver (2). CYP3A4 is involved in the metabolism of >50% of all drugs used in humans (3)(4). Interindividual differences in CYP3A4 expression may account for the observed interindividual differences in pharmacokinetics of drugs metabolized by this enzyme (4)(5)(6). Variations in CYP3A4 expression may be caused by factors inhibiting or stimulating transcription and/or translation (e.g., concomitant drug administration) and by genetic polymorphisms. In a recent study, an A(−290)G substitution was described in the 5′ regulatory region of the CYP3A4 gene (7)(8). This allele was termed CYP3A4-V but was recently also referred to as CYP3A41B (9). The allelic frequency, determined by conformation-sensitive gel electrophoresis, was estimated as 9.6% among US Caucasians (7). In 94 healthy unrelated male volunteers, 3.2% were found to be homozygous and 12.8% heterozygous for the CYP3A4-V allele (7). In a recent publication, the allelic frequency was shown to display major interethnic differences, ranging from 0.0% among Chinese-Americans to 54.6% among black Americans (10)(11). The CYP3A4-V allele has recently been associated with higher clinical stage and grade of prostate cancer (11)(12)(13). In this study, a simple and specific PCR-restriction fragment length polymorphism (RFLP) procedure was developed that can be used in routine screening procedures to detect the CYP3A4-V polymorphism. EDTA-whole blood was collected from 199 healthy Caucasian volunteers after informed consent. The study was approved by the Medical Ethical Committee of the University Hospital …