伴有11q23／MLL重排的儿童急性髓系白血病的临床及实验室分析

Clinical and experimental studies of childhood acute myeloid leukemia with llq23/MLL rearrangements

目的分析伴有11q23／混合谱系白血病（mixed lineage leukemia，MLL）基因重排的儿童急性髓系白血病（acute myeloid leukemia，AML）的临床和实验室特点。方法采用骨髓细胞短期培养法和R显带技术对234例初诊AML患儿进行核型分析；采用逆转录一多重巢式聚合酶链反应（多重PCR）技术检测MLL融合基因以及JlⅥLL部分串联重复；采用双色MLL基因探针，对其中2例核型分析具有11q23易位而多重PCR检测肌L融合基因呈阴性的患儿样本进行间期双色荧光原位杂交（dual-colorfluorescenceinsituhybridization，D-FISH）MLL重排检测。结果R显带提示234例初诊AML患儿中，20例（M514例、M44例、M22例）有涉及11q23的易位，包括t（9；11）（p22；q23）12例，t（1；11）（q21；q23）3例，t（6；11）（q27；q23）2例，t（11；19）（q23；p13）、t（5；11）（q31；q23）和t（X；11）（q24；q23）各1例。多重PCR证实其中18例有MLL的融合转录本，有2例阴性，但D-FISH均检出MLL重排；在其余AMI。患儿的样本中检出8例（M54例、M42例、M2和M6各1例）有MLL部分串联重复。本组AML患儿中，11q23／MLL重排的总检出率11．97％（28／234），其中85．7％（24／28）的病例为M4／M5亚型。本组28例伴有11q23／MLL重排患儿，治疗后完全缓解率为53．8％，与对照组（以同期伴有其他异常核型和正常核型的AML—M4／M5患儿共27例作为对照）的90．5％相比，差异有统计学意义（P〈0．05）。其中2例患儿接受了强烈化疗，分别生存达81和66个月。4例接受了异基因干细胞移植，已分别生存21、20、16和11个月，至今仍在完全缓解中。本组28例伴有11qga／MLL重排患儿的中位生存期为11个月，对照组为15个月，差异无统计学意义（P〉O．05）。结论伴有11q23／MLL重排的AML患儿和单核系白血病高度相关。11q23易位和MLL部分串联重复是相互排斥的，二者预后均较差。采用强烈化疗和异基因于细胞移植有望获得较好疗效。多重PCR联合染色体核型分析和D-FISH技术是对初诊AML患者进行各种MLL重排筛检的有效方法。

Objective To explore clinical and experimental features of 28 cases of childhood acute myeloid leukemia （AML） with 11q23/MLL gene rearrangements. Methods Karyotypes of 234 cases of de novo childhood AML were analyzed using short-term culture of bone marrow cells and R-banding. The fusion transcripts involving MLL gene and partial tandem duplication of MLL （MLL-PTD） were detected by multiple reverse transcription-polymerase chain reaction （RT-PCR） assay. Two cases with 11q23 translocation by karyotypic analysis but with negative result of multiple RT-PCR were studied with MLL dual-color fluorescence in situ hybridization （D-FISH）. Results R-banding karyotypic analysis has revealed 20 cases with 11q23 translocation （14 cases with M5, 4 cases with M4, 2 cases with M2）, including 12 cases with t（9;11）（p22;q23）, 3 cases with t（1;11）（q21;q23）, 2 cases with t（6;11）（q27;q23）, 1 case with t（11;19）（q23;p13）, 1 witht（5;11）（q31;q23）, and 1 witht（X;11）（q24;q23）. Eighteen cases with 11@3 translocation having fusion transcripts involving MLL genes were confirmed with multiple RT-PCR; 2 cases showed negative results, but they were confirmed to have MLL rearrangements by D-FISH. MLL-PTD wasalso detected in 8 cases （4 cases M5, 2 cases M4, M2 and M6, one case each） from the other childhood AML cases. The total incidence of llq23/MLLgene rearrangements was 11.97% （28/234）, and most of patients （85.7%, 24/28） were M4/M5. The complete remission （CR） rate after treatment for the 28 cases with MLL rearrangements was 53.8%, the difference was significant by statistics （P〈 0. 05） compared with 90.5% for the control group （M4/M5 childhood AML with other karyotypic abnormalities or normal karyotype）. Of them, 2 cases receiving intensive chemotherapy survived for 81 and 66 months, respectively, 4 cases receiving allogeneic stem cell transplantation survived for 21, 20, 16 and 11 months, respectively, and are still alive with CR. The medium survival （MS） time for 28 cases with 11q23/MLL rearrangements was 11 months, whereas the MS for control group was 15 months. The difference was not statistically significant （P^0.05）. Conclusion The llq23/MLL rearrangements is highly correlated with the occurrence of monocytic leukemia （M4 and M5）. The 11q23 translocation and MLL-PTD are mutually exclusive, though both are indicative of poor prognosis. Intensive chemotherapy and allogeneic stem cell transplantation may ameliorate the clinical outcome. Multiple RT-PCR combined with karyotypic analysis and D-FISH are useful for screening the 11q23/MLL rearrangements in childhood AML.