Allele and genotype frequencies of CYP2B6 and CYP3A5 in the Japanese population.

OBJECTIVE: The goal of this study was to determine the frequencies of allelic variants of CYP2B6and CYP3A5 in the Japanese population. METHODS: Genotyping of CYP2B6 (*2, *3, *4, *5, *6, and *7) and CYP3A5 ( *2, *3, *4, *5, and *6) was carried out in 265 unrelated Japanese subjects by polymerase chain reaction (PCR), restriction fragment length polymorphism and allele-specific, real-time PCR assays. RESULTS: Allele frequencies for CYP2B6*2, *3, *4, *5, *6, and *7 in 256 Japanese subjects were 0.047, 0, 0.093, 0.011, 0.164, and 0, respectively. Ethnic variation in allele frequencies relative to that in Caucasian subjects was observed for CYP2B6*4 (0.093 vs 0.040), *5 (0.011 vs 0.109), *6 (0.164 vs 0.256), and *7 (0 vs 0.030). Allele frequencies for CYP3A5*2, *3, *4, *5, and *6 in 265 Japanese subjects were 0, 0.740, 0, 0.004, and 0, respectively. The frequency of the CYP3A5*1 allele is 2.8 times higher in Japanese than in Caucasians. CONCLUSIONS: Our results contribute to a better understanding of the molecular basis of ethnic differences in drug response, which may help to improve individualization of drug therapy and offer a preliminary basis for more rational use of drugs that are substrates for CYP2B6 and CYP3A5 in the Japanese population.

Allele and genotype frequencies of polymorphic cytochromes P450 (CYP2C9, CYP2C19, CYP2E1) and dihydropyrimidine dehydrogenase (DPYD) in the Egyptian population.

AIMS: The goal of this study was to determine the frequencies of important allelic variants of CYP2C9, CYP2C19, CYP2E1 and DPYD in the Egyptian population and compare them with the frequencies in other ethnic populations. METHODS: Genotyping of CYP2C9 (*2 and *3), CYP2C19 (*2 and *3), c2 variant of CYP2E1 and DPYD alleles (*2 A-*6 ) was carried out in a total of 247 unrelated Egyptian subjects. An allele-specific fluorogenic 5' nuclease chain reaction assay was applied for detection of CYP2C9 and CYP2C19 variants. Other variants of the CYP2E1 and DPYD genes were determined using polymerase chain reaction (PCR)-restriction fragment length polymorphism and allele-specific PCR based assays. RESULTS: CYP2C9 allele frequencies in 247 Egyptian subjects were 0.820 for CYP2C9*1, 0.120 for CYP2C9*2 and 0.060 for CYP2C9*3. For CYP2C19, the frequencies of the wild type (CYP2C19*1) and the nonfunctional (*2 and *3) alleles were 0.888, 0.110 and 0.002, respectively. CYP2C19*3, which is considered an Asian mutation, was detected in one subject (0.40%) who was heterozygous (*1/*3). Two subjects (0.80%) were homozygous for *2/*2, while no compound heterozygotes (*2/*3) or homozygotes for *3 were detected. For CYP2E1, only four subjects (1.70%) had the rare c2 variant, expressed heterozygously, giving an allele frequency of 0.009. Five variants of DPYD were analysed, with no splice sites (*2 A) or DeltaC1897 (*3) found in this population. The frequencies of other variants were 0.028, 0.115 and 0.090 for *4, *5 and *6, respectively. CONCLUSIONS: Comparing our data with that obtained in several Caucasian, African-American and Asian populations, we found that Egyptians resemble Caucasians with regard to allelic frequencies of the tested variants of CYP2C9, CYP2C19, CYP2E1 and DPYD. Our results may help in better understanding the molecular basis underlying ethnic differences in drug response, and contribute to improved individualization of drug therapy in the Egyptian population.

Allele and genotype frequencies of polymorphic DCP1, CETP, ADRB2, and HTR2A in the Egyptian population.

OBJECTIVE: The goal of this study was to determine the frequencies of important allelic variants of two drug targets, dipeptidyl carboxypeptidase ( DCP1) and cholesteryl ester transfer protein ( CETP), and two other drug receptors, beta-2 adrenergic receptor ( ADRB2) and 5-hydroxy tryptamine 2A receptor ( HTR2A), in the Egyptian population and compare them with the frequencies in other ethnic populations. METHODS: A sensitive real-time polymerase chain reaction assay was developed and successfully applied for genotyping of the consensus (wild-type) alleles plus five variants of four genes: DCP1 [the insertion allele ( I) versus the deletion allele ( D)], CETP*TaqI ( B1 versus B2), ADRB2*R16G, ADRB2*Q27E, and HTR2A*102T>C. This study was carried out in 242 unrelated Egyptian subjects and is the first to describe these allelic variants in the Egyptian population. RESULTS: The frequencies of the tested alleles were found as: DCP1 ( I: D, 0.32:0.68), CETPTaqI ( B1: B2, 0.65:0.35), ADRB2*R16G ( Arg16: Gly16, 0.57:0.43), ADRB2*Q27E ( Gln27: Glu27, 0.76:0.24), and HTR2A*102T>C ( T102: C102, 0.53:0.47). The common Arabian ancestors of the Egyptians, Spanish, Saudi, and Emirate had created a common pattern of distribution of some allelic variants ( DCP1 and CETP). However, in the genotyping of ADRB2, the frequency of the polymorphism at codon 16 was found to be similar to the Chinese population, whereas that at codon 27 was similar to African-Americans with significant differences than other Caucasian populations. The frequency of the HTR2A*102T>C variant appeared to be similar to many Caucasian populations and African-Americans. CONCLUSIONS: We have explored the frequencies of important allelic variants DCP1, CETP, ADRB2, and HTR2A among the Egyptian population focusing on the ethnic diversity in the distribution of the tested mutant alleles. Our results may help in better understanding the observed ethnic variation in angiotensin-converting enzyme inhibition and atherosclerosis therapy. It also may contribute to better characterization of interethnic differences in isoprenaline and clozapine response, which will have implications for the cost effective and rational prescribing of these drugs.

Genotyping of the N-acetyltransferase2 polymorphism in the prediction of adverse drug reactions to isoniazid in Japanese patients.

To investigate the association between NAT2 genotypes and the incidence of isoniazid (INH)-induced adverse reactions, in the hope of identifying a pharmacogenetic approach that could be useful in the prediction and prevention of adverse reactions in Japanese patients, we retrospectively studied the genotypes of NAT2 in 102 Japanese patients treated with INH (without rifampicin co-administration). The subjects were classified into three groups according to their genotypes: rapid-type, intermediate-type, and slow-type. The clinical conditions of the patients were followed-up in order to evaluate the development of any adverse drug reactions (ADRs) and correlate them with patient genotypes. Six out of the 102 patients (5.9%) developed various ADRs following INH treatment. These reactions included nausea/vomiting, fever, visual impairment, and peripheral neuritis. We found a statistically significant difference between the incidence of ADRs and NAT2 genotype. The incidence of ADRs was significantly higher in the slow type than in the other two types, as 5 out of the 6 ADR patients were of the slow-type, and the other one was of the intermediate-type, while no patients of the rapid-type developed any ADRs. The results indicated that the genes coding for slow acetylation were associated with the incidence of serious ADRs following INH treatment. Our findings suggest that determination of NAT2 genotype might be clinically useful in the evaluation of patients at high risk of developing ADRs induced by INH.