巯嘌呤甲基转移酶基因多态性位点与酶活性的关系  

Relationships between thiopurine methyltransferase gene polymorphisms and its enrymatic activity

作　　者：马晓莉[1] 吴敏媛[1] 胡亚美[1] 朱平[2] 李志刚[1] 

机构地区：[1]首都医科大学附属北京儿童医院血液中心,北京100045 [2]北京大学第一医院血液科

出　　处：《中华肿瘤杂志》2006年第6期456-459,共4页Chinese Journal of Oncology

摘　　要：目的研究巯嘌呤甲基转移酶(TPMT)基因型与酶活性的关系,为根据不同基因型、酶活性对巯嘌呤类药物的反应而改进治疗方案提供依据。方法应用以PCR为基础的限制性内切酶消化、变性高效液相色谱分析和SNaPshot定点的序列分析等方法,并结合DNA直接测序,对250例健康献血员、100例脐血标本和280例急性白血病患者,检测TPMT基因第5外显子G238C、第7外显子G460A和第10外显子A719G的3个多态性位点。应用高效液相色谱分析技术,测定3组人群的红细胞内TPMT活性。结果本研究组人群TPMT基因外显子区3个位点的多态性频率均低,为3．5%。变异的位点为第10外显子A719G,且均为杂合变异。红细胞内TPMT活性波动范围为6～32 U,TPMT＞12 U者占95．1%(599例),6～12 U者占4．9%(31例)；未发现有TPMT活性缺乏者。健康献血员、脐血标本和急性白血病患者的TPMT杂合变异者,红细胞内平均TPMT活性分别为9．1 U、9．3 U和9．07 U,均分别低于其同组TPMT野生型者的17．6 U、17．67 U和18．6 U(P＜0．01)。在16例健康献血员和脐血标本中,在15例急性白血病患者的红细胞内TPMT低活性者中,分别有4例和6例未发现所检测的TPMT外显子3个SNP位点的变化,提示红细胞内TPMT活性还受其他因素的影响。结论TPMT基因多态性影响酶的活性,即TPMT杂合变异者,其TPMT活性降低,从而影响巯嘌呤类药物的治疗效应。根据不同TPMT基因型、酶活性对巯嘌呤类药物的反应制定治疗方案,可进一步提高治疗的有效性和安全性。Objective To investigate the relationship between the thiopurine methytransferase （TPMT） gene polymorphisms and its enrymatic activity, and to clarify the significance of TPMT activity and gene polymorphisms on individualized therapy with thiopurines. Methods The TPMT activity and gene polymorphisms were determined in an unrelated population of 250 Chinese healthy blood donors, 100 cords blood and 280 patients with acute leukemia. The TPMT genotyping assay was based on polymerase chain reaction （PCR）, restriction digestion of PCR products, denaturing high-porformance liquid chromatography （DHPLC） and SNaPshot sequencing and direct DNA sequencing in the TPMT exon 5 （G238C）, TPMT exon7 （G460A） and TPMTexon10 （A719G）. Erythrocyte TPMT activity was measured by high-performance liquid chromatography （HPLC）. Results The frequency of TPMT polymorphism in 250 Chinese healthy blood donors, 100 cords blood and 280 patients with acute leukemia was low （3.5%） , and all the varied alleles were TPMT＊3C （exon 10A719G）. All of them were TPMT＊ 1/TPMT＊ 3C heterozygote. The TPMT activity was between 6 and 12 U. The activity in 95.1% was more than 12 U （13 ～32 U） , while the activity in others （4.9%） was 6 ～ 12 U. TPMT activity and genotype were concordant. Of 630 subjects evaluated, TPMT activity of heterozygous individuals in Chinese healthy blood donors, cords blood and acute leukemia patients were 9.1 U, 9.3 U and 9.07 U, respectively, significantly lower than that in general population （17.6 U,17.67 U and 18.6 U, respectively）. In the samples analyzed, ten subjects with heterozygous phenotypes （6/15 acute leukemia children and 4/16 healthy blood donors and cords blood） did not have TPMT＊2, TPMT＊ 3A or TPMT＊ 3C. Therefore, other factors may affect on TPMT activity.Conclusion TPMT gene polymorphisms and its activity were concordant. The heterozygotes had low TPMT activity. Therefore, detection of TPMT genotype and its activity is useful. These findings hold a pre

关 键 词：巯嘌呤甲基转移酶基因 巯嘌呤甲基转移酶基因型 巯嘌呤甲基转移酶活性 多态性 巯嘌呤类药物 

分 类 号：R733.7[医药卫生—肿瘤] R394[医药卫生—临床医学]