两种BCR/ABL探针在Ph阳性白血病荧光原位杂交检测中的不同信号模式及其意义

目的 比较BCR/ABL双色额外信号探针(dual color extra-signal BCR/ABL probe,ESFISH探针)及BCR/ABL双色双融合探针(dual color dual fusion BCR/ABL probe,D-FISH探针)在Ph阳性白血病荧光原位杂交(fluorescence in situ hybridization,FISH)检测中信号模式的差异,探讨它们的诊断价值.方法 分别采用D-FISH和ES-FISH探针对74例伴有单纯t(9;22)(q34;q11)及37例伴有变异Ph易位或复杂核型异常的Ph阳性白血病患者骨髓细胞进行间期FISH检测.结果 所有单纯t(9;22)(q34;q11)易位的白血病患者应用两种探针均检测到BCR/ABL阳性信号,ES-FISH探针显示2个橙色信号、1个绿色信号和1个黄色信号模式,而D-FISH探针显示1个橙色信号、1个绿色信号和2个黄色信号模式.ES-FISH探针在9例(12.2%)Ph阳性白血病患者中识别次要BCR断裂位点(1个橙色信号、1个绿色信号和2个黄色信号),而D-FISH探针不能识别主要BCR和次要BCR断裂位点;D-FISH探针在8例(10.8%)Ph阳性白血病中区分ABL基因单独缺失(1个橙色信号、2个绿色信号、1个黄色信号)和ABL、BCR基因共同缺失(1个橙色信号、1个绿色信号和1个黄色信号),ES-FISH则不能区分之.检测变异Ph易位和含Ph易位的复杂核型异常时,两种探针的信号模式分别有4种和6种之多,且以不典型者居多,对于它们的精确解释必须依赖常规染色体分析和中期FISH结果 .结论 ES-FISH及D-FISH探针由于BCR探针大小及覆盖区域不同,在Ph阳性白血病的FISH检测中显示不同信号模式,可分别作为Ph+急性淋巴细胞白血病和慢性髓系白血病患者FISH检测的首选.若采用伊马替尼治疗,主要BCR断裂点和次要BCR断裂点、伴或不伴有衍生9号染色体部分序列缺失均不影响预后,但鉴于ES-FISH探针性价比优于D-FISH探针,推荐其作为Ph阳性白血病FISH检测的首选.

The different signal patterns of two FISH probes in the FISH detection of Ph-positive leukemia and their clinical significance

Objective To compare the signal patterns of dual color extra-signal BCR/ABL probe (ESFISH) and dual color dual fusion BCR/ABL probe (D-FISH) in the fluorescence in situ hybridization (FISH) detection of Ph-positive leukemia, and to explore their diagnostic value. Methods ES-FISH probe and D-FISH probe were used, respectively, to detect the BCR/ABL fusion gene in 74 cases with typical t (9;22)(q34;q11) and 37 cases with variant t(9;22)(q34;q11) translocation or complex karyotypic abnormalities containing Ph translocation. Results The BCR/ABL fusion gene in all cases with typical t (9;22)(q34;q11) could be detected by both FISH probes. D-FISH had a signal pattern of 1O1G2F, while ES-FISH showed a signal pattern of 2O1G1F. ES-FISH enables the minor breakpoint cluster region to be identified in 9 cases (12.2%) of Ph-positive leukemia, whereas D-FISH could not differentiate the minor breakpoint cluster region from major breakpoint cluster region. D-FISH could distinguish simple ABL gene deletion from simultaneous deletion of the ABL and BCR genes in 8 cases (10.8%) of Ph-positive leukemia patients, but ES-FISH could not.For variant Ph translocation or complex karyotypic abnormalities containing Ph translocation, each FISH probe showed four or six types of signal pattern, most of which were atypical.The exact interpretation was dependent on conventional karyotypic analysis and FISH on metaphases. Conclusion ES-FISH and D-FISH probes displayed different signal patterns in Ph-positive leukemia due to their differences in size and covered regions. ES-FISH and D-FISH probes may be selected as better probe for Ph-positive acute lymphocytic leukemia and Ph-positive chronic myeloid leukemia,respectively. When imatinib was used for treatment, there was no preference between ES-FISH and D-FISH probe, because major breakpoint cluster region, minor breakpoint cluster region and partial sequence deletion of derivative chromosome 9, would not affect the prognosis of Ph positive leukemia. However,considering that ES-FISH probe has a better cost-performance than D-FISH probe does, it is recommended as first choice.