MTHFR C677T和RFC1 G80A基因多态性对急性淋巴细胞白血病患儿大剂量甲氨蝶呤化疗不良反应的影响

Influence of MTHFR C677T and RFC1 G80A Gene Polymorphisms on Adverse Reactions of High Dose Methotrexate Chemotherapy in Children with Acute Lymphoblastic Leukemia

目的探讨MTHFR C677T和RFC1G80A基因多态性是否对儿童ALL大剂量甲氨蝶呤（HD-MTX）化疗后不良反应有影响。方法回顾性分析53例ALL患儿（2-12岁）HD-MTX化疗后的不良反应,并检测患儿MTHFR C677T和RFC1G80A基因型,探讨不良反应与基因型的相关性。采用PCR-限制性内切酶片段长度多态性技术（PCR-RFLP）扩增基因片段并酶切电泳观察分析MTHFR C677T和RFC1 G80A的多态性。患儿HD-MTX化疗后发生的不良反应按照WHO标准统一评价,采用免疫偏振荧光法（FPIA）检测HD-MTX化疗44h后MTX血清药物水平。结果53例ALL患儿中,MTHFR677CC、677CT和677TT基因型分别占28.3%、43.4%和28.3% RFC180GG、80GA和80AA基因型分别占13.2%、58.5%和28.3%。接受HD-MTX化疗的53例ALL患儿中,总体不良反应发生率为62.3%（33/53例）,而RFC180AA基因型患儿发生不良反应的可能性是RFC180GG基因型患儿的10倍（OR=10.00,95%CI：1.26-79.34,P=0.03）。在有不良反应的患儿中,RFC180A等位基因携带频率（70.5%）显著高于RFC180G（51.1%,P=0.04）,携带RFC180A等位基因可增加HD-MTX化疗后不良反应的发生风险（OR=2.29,95%CI：1.02-5.10）。与其他基因型患儿比较,RFC180AA基因型者发生Ⅱ度以上肝损伤的风险加大（OR=5.6,95%CI：1.536-20.420,P=0.006）,并且发生排泄延迟的概率也较其他基因型者高（OR=5.061,95%CI：1.373-18.654,P=0.028）。结论RFC1G80A基因多态性有望成为对ALL患儿HD-MTX毒性反应进行预测的有效指标之一。

Objective To investigate whether genetic polymorphisms of methylenetetrahydrofolate reductase （MTHFR C677T） and reduced folate carrier（RFC1 G80A） were associated with toxicity of high dose methotrexate（ HD- MTX） in children with acute lymphoblastic leukemia （ALL）. Methods HD - MTX - treated children with ALL （2 to 12 years old, n = 53 ） were selected frum inpatient and used for a retrospective study to examine the correlation between genetic polymorphisms of MTHFR C677T and RFC1 G80A and toxicity of HD - MTX. Gene fragment was amplified by restriction fragment length polymorphism polymerase chain reetion （PCR -RFLP）, and MTHFR C677T or RFC1 GSOA polymorphisms were analyzed by enzyme electrophoresis. The MTX serum concentration was measured by a fluorescence polarization immunoassay （FPIA）. The adverse reactions of children received HD -MTX chemotherapy was evaluated using WHO common toxicity criteria and serum concentration of MTX at 44 h were recorded. Results Of all the cases, the frequencies of MTHFR 677CC, 677CT and 677TT genotype were 28.3% , 43.4% and 28.3% , while the frequencies of RFCI 80GG, 80GA and 80AA genotype were 13.2% , 58.5% and 28.3%, respectively. The overall incidence rate of adverse reactions were 62.3% （33/53 cases）. The probability of adverse reactions was 10 - fold higher in carriers of RFC1 80AA genotype as compared with patients with 80GG genotype （ OR = 10. 00, 95% CI： 1.26 - 79.34, P = 0.03 ）. The frequency of A allele among adverse reactions group （70.5%） was significantly higher than G allele （51.1%, P = 0.04）. RFC1 80A variant allele increased the risk for overall MTX toxicity （OR =2. 29, 95%CI：1.02 -5.10）. The incidence rate of hepatoxicity above Ⅱ degree in RFCI 80AA genotype was significantly higher than other genotypes （ OR = 5.6, 95% CI： 1. 536 - 20. 420, P = 0.006）. Moreover, the delayed elimination of MTX was noted more frequently for patients with RFCI 80AA genotype （OR =5. 061, 95% CI： 1. 373 - 18. 654, P = 0. 028 ）. Conclusion This study suggests that RFC1 G80A may serves as predictors of toxicity of HD - MTX chemotherapy in children with ALL.