汉族儿童细胞色素P450单核苷酸多态性及其代谢表型分布的研究

Distribution of single nucleotide polymorphisms of cytochrome P450 genes and mtabolic phenotypes in Han children

目的了解中国汉族人群细胞色素P450(CYP450)重要单核苷酸多态性(SNPs)及其代谢表型的分布情况,丰富相应位点中国汉族人群的遗传学数据库。方法选择首都医科大学附属北京儿童医院300例中国汉族分析人群的DNA样本,应用实时PCR基因分型法结合测序,对CYP450 6个亚型的8个SNPs位点:CYP2C9 1075A>C、CYP2C19 636G>A、CYP2C19 681G>A/C、CYP2D6 100C>T、CYP2E1-1053C>T、CYP2E1 7632T>A、CYP3A4 878 T>C和CYP3A56986A>G的基因型进行检测,计算基因型和等位基因频率;同时初步获得CYP450 6个亚型代谢表型的分布特点。结果①中国汉族分析人群CYP2C19 681G>A/C、CYP2D6 100C>T和CYP3A5 6986A>G位点野生型杂合子的基因型频率较高,分别为46.3%、47.0%和43.7%,其突变等位基因的频率也较高,分别为58.8%、34.5%和63.5%;CYP2C9 1075A>C、CYP2C19 636G>A、CYP2E1-1053C>T、CYP2E1 7632T>A和CYP3A4 878T>C位点野生型纯合子的基因型频率较高,分别为100%、89.3%、61.3%、58.3%和98.0%。②中国汉族分析人群CYP450代谢表型的分布情况为CYP2C9、CYP2C19、CYP2D6、CYP2E1、CYP3A4和CYP3A5的快代谢型和超快代谢型比例分别为100%,83.3%,64.7%,95.0%,100%和58.3%;CYP2C19、CYP2D6和CYP3A5中间代谢型和慢代谢型比例分别为11.4%、35.3%和41.7%。结论CYP2D6 100C>T、CYP2C19 681G>A/C和CYP3A5 6986A>G位点在中国汉族人群中的突变频率较高,且其中间代谢型和慢代谢型比例较高,可为后续优化SNPs入选位点和指导临床个体化用药提供依据。

Objective Cytochrome P450（CYP450） is a family of the body′s more powerful detoxic enzymes that involve in the biotransformation of various endogenous and exogenous compounds including clinical drugs.Genetic and phenotypic polymorphism of CYP results in the individual differences of xenobiotic metabolisms.The aim of this study was to understand the genetic polymorphism and the metabolic phenotype of CYP450 subtypes in normal Chinese Han population,and to obtain the genetic data of these loci in Chinese Han population.Methods We identified 300 children who were randomly sampled from the outpatient and inpatient departments from March,2005 to December,2008.Members of these children were of Chinese Han nationality.The mean age of them was 5.0 years（SD： 4.3;range： 0.17-16.0 years）,and the proportion of female children was 39.3%.Information on these children were obtained from the patients′ files,and all the participants and their parents provided written informed consent.Genomic DNA was extracted from peripheral blood by EDTA anticoagulation,using a standard salting-out procedure.The concentration and purity of DNA were estimated spectrophotometrically.Eight important SNPs in 6 important CYP450 subtypes（CYP2C9 1075AC,CYP2C19 636GA,CYP2C19 681GA/C,CYP2D6 100CT,CYP2E1-1053CT,CYP2E1 7632TA,CYP3A4 878TC and CYP3A5 6986AG） were chosen for this study.The genotypes of these SNPs in 300 random Chinese Han children were typed by real-time PCR,and then by sequencing to examine the reliability of the results.The frequencies of genotypes and alleles were calculated by SHEsis on-line software.And the Hardy-Weinberg equilibrium（HWE）,which indicates the absence of a discrepancy between the genotypic and allelic frequencies,was carried out using SPSS software,version 13.0.Results The frequencies of wild heterozygote on the loci of CYP2C19 681GA/C,CYP2D6 100CT and CYP3A5 6986AG（46.3%,47.0% and 43.7%） were high in Chinese Han population,and the frequencies of mutant homozygote on the loci of CYP2D6 and CYP3A5 were higher than those of wild homozygote（35.3% vs 17.7%,41.7% vs 14.7%）,so the frequencies of the corresponding alleles were also higher（34.5%,58.8% and 63.5%）.The frequencies of wild homozygote on the loci of CYP2C19 636GA,CYP2E1-1053CT,CYP2E1 7632TA and CYP3A4 878TC（100%,89.3%,61.3%,58.3% and 98.0%） were high in Chinese Han population,the genetic variability on the loci of CYP2C9 1075AC and CYP3A4 878TC（0,2.0%） were especially rare in Chinese Han population.The metabolic phenotypes of CYP2C19,CYP2D6 and CYP3A5 in Chinese Han population were mostly intermediate and/or poor metablizer（11.4%,35.3% and 41.7%）.The metabolic phenotypes of CYP2C9,CYP2E1 and CYP3A4 in Chinese Han population were mostly extensive and/or ultrarapid metablizer（100%,95.0% and 100%）.Conclusions The mutation frequencies of these three SNPs（CYP2D6 100CT,CYP2C19 681GA/C and CYP3A5 6986AG） are high in random Chinese Han population,and the frequencies of these three subtypes with intermediate and poor metablizer were also high,so they could be the candidate loci for subsequent optimization grouping SNPs research and guiding the individualized medication.