Objective The activities of folylpolyglutamate synhase ( FPGS ) and gamma-glutamyl hydrolase ( GGH ) dynamically determine the intracellular concentrations of methotrexate( MTX ) and its active metabolites, methotrexate polyglutamates( MTXPG),in ALL cells,is the key determinant of its antileukemic effects. To investigate whether the expressions of FPGS,GGH and the ratio of FPGS to GGH gene expression between pediatric patients with ALL and the normal control children are different,and if they are correlated with chemotherapeutic efficacy of MTX in ALL patients. Methods The children newly diagnosed with ALL at Shenzhen Childrenˊs Hospital were recruited as ALL group,children with nonmalignancy as the control group. Bone marrow samples from ALL group and peripheral blood samples from the control group were analyzed for the expressions of FPGS and GGH genes by SYBR Green relative quantitative real-time PCR. The difference of FPGS and GGH gene expressions was compared between ALL group and the control group. The subjects were divided into high- and low-expression subgroups according to the median of FPGS and GGH expression level,the discrepancies of MTX effect,toxicity and prognosis were analyzed by different expression subgroups of FPGS and GGH. Results Sixty-one children with newly diagnosed ALL at mean age 4. 6 years were enrolled in this study,including 39 males and 22 females;thirty children averagely aged 4. 2 years were enrolled in the control group,including 19 males and 11 females. The median(P25 _P75)expressions of FPGS,GGH and the ratio of FPGS to GGH gene expression in ALL group(FPGS/β-actin,GGH/β-actin,FPGS/GGH)were 14. 14(6. 52,27. 31),9. 34(4. 97,14. 22)and 1. 74 (0. 76,2. 91),significantly higher than 0. 59(0. 35_1. 23),3. 00(0. 94_5. 26)and 0. 26(0. 13_1. 00)in the normal group ( P<0. 01). The recurrence rate was 3. 7%(1/27)in the subjects with higher FPGS gene expression verse 23. 3% in those with lower gene expressions(P<0. 05). High expression of FPGS gene was correlated with higher risk of neutropenia(OR=4. 167, 95%CI:1. 65_10. 52,P=0. 003). High expression of GGH increased the risk of hepatotoxicity( OR=5. 61,95%CI =1. 14 _27. 47,P=0. 033). No correlation was found between the ratio of FPGS to GGH gene expression and chemotherapeutic effect, toxicity of MTX in this study. Conclusion The expressions of FPGS,GGH and the ratio of FPGS to GGH gene expression in ALL children were higher than that in the control children. Expression of FPGS gene is associated with chemotherapeutic effect,toxicity of MTX in ALL children.%目的：研究叶酰多聚谷氨酸合成酶（ FPGS）、γ-谷氨酰水解酶（ GGH）基因表达水平在急性淋巴细胞白血病（ALL）患儿和正常儿童中是否存在差异，并分析不同基因表达水平与大剂量甲氨蝶呤（ MTX）疗效、毒副作用及预后的相关性。方法以深圳市儿童医院（我院）血液科收治的ALL初诊且接受大剂量MTX化疗患儿为ALL组，以非造血系统恶性疾病儿童为对照组；采用SYBR Green荧光定量RT-PCR检测ALL组骨髓和对照组外周血中FPGS与GGH基因相对表达水平，比较ALL组和对照组FPGS与GGH基因表达水平差异。进一步按照ALL组FPGS、GGH基因表达水平的中位数分为相应的高表达亚组和低表达亚组，分析FPGS、GGH不同表达亚组MTX疗效、毒副作用及预后的差异。结果2003年1月至2013年12月61例ALL患儿进入分析，男39例，女22例，平均年龄4.6岁；对照组纳入30例，男19例，女11例，平均年龄4.2岁。ALL组FPGS、GGH基因相对表达水平及其比值中位数（ P25~P75）分别为14.14（6.52~27.31）、9.34（4.97~14.22）和1.74（0.76~2.91），对照组分别为0.59（0.3~1.23）、3.00（0.94~5.26）和0.26（0.13~1.00），差异均有统计学意义（P均<0.01）。FPGS高表达和低表达亚组复发率分别为3.7%（1/27）和23.3%（7/30），差异有统计学意义（P<0.05）。FPGS基因表达水平升高增加发生中性粒细胞减少的风险（ OR=4.17，95%CI：1.65~10.52，P=0.003）。GGH基因高表达水平增加肝毒性的风险（ OR=5.61，95%CI：1.14~27.47，P=0.033）。未观察到FPGS/GGH比值对MTX疗效及毒副作用的影响。结论 ALL患儿FPGS、GGH基因表达水平及其比值高于正常儿童；FPGS基因表达水平对ALL患儿大剂量MTX疗效及毒副作用有一定的影响。
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