中国汉族炎症性肠病患者硫嘌呤甲基转移酶基因多态性研究

Gene polymorphisms research of thiopurine methyltransferase in Chinese Han nationality patients with inflammatory bowel disease

目的了解中国汉族炎症性肠病(IBD)患者硫嘌呤甲基转移酶(TPMT)基因多态性的分布情况,并探讨TPMT基因多态性与硫唑嘌呤(AZA)药物毒副作用的关系。方法 189名汉族IBD患者及273名健康对照者进入了研究。其中有43例患者接受了AZA治疗。分别采用引物特异性聚合酶链反应(PCR)和聚合酶链反应-限制性片段长度多态性分析(PCR-RFLP)方法对TPMT*2、TPMT*3B、TPMT*3C、TPMT*3A四个突变等位基因进行检测。对使用药物发生了毒副作用的患者进一步进行了TPMT基因外显子的PCR扩增及测序检测。结果所有的IBD患者和健康对照者均未检测到TPMT*2、TPMT*3A、TPMT*3B突变。IBD患者TPMT*3C突变等位基因频率为1.59%,与健康对照组相近(1.59%vs1.47%),经Fisher's确切检验显示,差异无统计学意义(P>0.05)。在对43例接受AZA治疗的IBD患者的随访中,观察到有4例患者发生了骨髓抑制,1例发生了肝脏毒性。5例患者均未检测到TPMT*2、TPMT*3A、TPMT*3B、TPMT*3C这4种常见的TPMT突变等位基因。进一步对该5例患者进行外显子测序工作,发现其中3例患者存在TPMT*1S突变杂合子,但为无义突变。结论在中国汉族IBD人群中,TPMT突变等位基因频率低,但AZA药物毒副作用的发生率并不低,AZA药物毒副作用无法完全通过TPMT基因突变来解释。

Objective To observe the distribution of gene polymorphisms of thiopurine methyltransferase in Chinese Han nationality patients with inflamtnatory bowel jisease and explore the relationship between TPMT polymorphisms and thiop- urine-related toxicity. Methods A total of 189 IBD patients and 273 healthy controls were enrolled. TPMT＊2, TPMT＊3A, TPMT＊3B and TPMT＊3C were analyzed using allele-specific polymerase chain reaction and polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP）. Exons of the TPMT gene from patients who suffered from azathioprine-induced toxicity were amplified and sequenced to detect TPMT mutations. Results No TPMT＊2, TPMT＊3A or TPMT＊3B mutant alleles were detected in all cases. The allele frequency of TPMT＊3C in the IBD group was 1.59%, which was similar to that of the healthy control group（1.47%）. There was no significant diffierenc between them（P〉0.05）. Forty three cases of IBD patients who treated with azathioprine therapy were followed-up. Four cases occurred myelotoxicity and 1 case occurred hepatotoxieity. No TPMT＊2, TPMT＊3A, TPMT＊3B or TPMT＊3C polymorphisms were detected in these 5 cases. After directly sequencing the exons of the TPMT gene in these 5 patients, a synonymous single-nueleotide polymorphism （TPMT＊IS） that did not alter the encoded amino acid was found in 3 patients. Conclusions The allele fre- quency of TPMT is low while the thiopurine-related toxicity of AZA is high relatively in IBD patients of Chinese Han na- tionality. Gene mutation can not explain the thiopurine-related toxicity of AZA completely.