RESUMO
AIM: To determine the distribution and frequency of functionally important allelic variants in the cytochromes P450 (CYP) 2C19, arylamine N-acetyltransferase 2 (NAT2), and thiopurine S-methyltransferase (TPMT) genes in the Han Chinese population and compare them with those of other ethnic populations.METHODS: Genotyping was carried out in a total of 210 unrelated Han Chinese volunteers derived from He-nan area. CYP2C19 variants ( * 2 and * 3), NAT2 variants ( * 6 and * 7), and TPMT variants ( * 3A, * 3B, and * 3C) were detected using polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP)assays. Detection of NA T2 * 5 and TPMT * 2 were performed using allele-specific polymerase chain reaction assays. RESULTS: Allele frequencies of CYP2C19 * 2 and * 3 occurred with 34.76 % and 6.4 %, respectively.Thirty-one persons ( 14.8 % ) carried two of these CYP2C19 alleles responsible for poor metabolizing activity.The frequencies of specif ic NAT2 alleles were 59.1%, 4.1%, 26.4 %, and 9.5 % for * 4 (wild-type), * 5(341C), * 6 (590A), and * 7 (857A), respectively. Genotyping of three different single nucleotide polymorphisms in the NA T2 gene revealed that the frequency of slow acetylators was 19.5 %. TPMT * 3C had an allelic frequency of 1.2 %. TPMT* 2, TPMT * 3A, or TPMT* 3B was not detected in the analysed samples. CONCLUSION: The overview of allele distribution for drug-metabolizing enzymes CYP2C19, NAT2, and TPMT among a Han Chinese population shows obvious difference to Caucasians. The data will be useful for clinical pharmacokinetic investigation and drug dosage administration to Han Chinese population.