急性白血病患儿混合谱系白血病基因重排阳性的生物学和临床特征

Clinical and molecular biologic characteristics of childhood acute leukemia with mixed lineage leukemia gene rearrangement

目的探讨儿童AL中混合谱系白血病（mixed lineage leukemia，MLL）基因重排的发生率、融合基因的常见类型及临床特征。方法利用巢式反转录聚合酶链反应检测MLL融合基因，对87例阳性患儿的骨髓细胞形态学、免疫学、分子生物学、染色体特征以及临床表现进行回顾性分析。结果儿童AL1209例中87例有MLL基因重排，其中ALL发生率为6．41％，AML发生率为9．36％。58例ALL均为B—ALL，28例AML中M517例，M45例，M24例，M3、M6各1例，混合性白血病1例，为髓系伴T淋巴系表达。76例进行染色体核型分析，45例（59．21％）可检出克隆性染色体异常，其中28例累计11q23（36．84％）。检测到7种融合基因亚型：MLL—AF9及dupMLL各25例，MLL—AF417例，MLL—AF109例，MLL—ENL8例，MLL—AF1q2例．MLL—AF61例。MLL-AF4、MLL—AF9、MLL—AF10、MLL—ENL及dupMLL在白血病类型、年龄及WBC计数比较差异均有统计学意义（P均〈0．05）。结论儿童MLL基因重排白血病ALL中以B．ALL多见，AML以M5、M4多见；最常见的融合基因亚型为MLL—AF9、MLL—AF4和dupMLL。MLL融合基因类型不同，可能表现为不同的临床特征，其中MLL—AF4、MLL—ENL可能多见于ALL，初诊WBC较高，发病年龄较小。

Objective To analyze the frequency of mixed lineage leukemia （MLL） gene rearrangement, the frequent types of fusion genes and clinical characteristics of childhood acute leukemia （AL） with MLL gene rearrangement. Methods Morphological and molecular characteristics of 87 AL patients with MLL gene rearrangement were studied and analyzed. MLL fusion gene was detected by way of reverse transcription polymerase chain reaction （RT- PCR）. Results Eighty-seven cases with MLL gene rearrangement were found in 1209 AL patients with incidence of 6.41% and 9.36% respectively in ALL and in acute myelocytic leukemia （AML） respectively. Fifty-eight cases of ALL were all B-ALL,28 cases of AML included 17 cases of M5,5 cases of M4,4 cases of M2,1 case of M3 and 1 case of M6. While there was 1 case of mixed of lineage leukemia and myeloid and T-lymphoblastie antigen presentation. The clonal chromosomal aberration was detected in 45 out of 76 cases （59.21%） , and chromosome 11 q23 aberration were observed in 28 cases （36.84%）. There were 7 different kinds of fusion genes, including MLL-AF9 in 25 cases, dupMLL in 25 cases, MLL-AF4 in 17 cases, MLL-AFIO in 9 cases, MLL-ENL in 8 cases, MLL-AFI q in 2 cases, and MLL-AF6 in 1 case. Among the cases of MLL-AF4, MLL-AF9, MLL-AF10, MLL-ENL and dupMLL, there were statistical differences in lineage, age and initial white blood cell count （WBC） （ all P 〈 0.05 ）. Conclusions In childhood AL with MLL gene rearrangement, B-ALL is more common in ALL, whereas M5 and M4 are more common in AML. The common types of fusion genes are dupMLL, MLL-AF9 and MLL-AF4. Patients with the different kinds of MLL fusion gene may present different clinical characteristics. The most common ALL cases are those with MLL/AF4 and MLL/ENL who may be younger with higher WBC than the others.