Martinez-Climent J A, Thirman M J, Espinosa R, Le Beau M M, Rowley J D
Department of Medicine, University of Chicago Medical Center, IL 60637, USA.
Leukemia. 1995 Aug;9(8):1299-304.
Cytogenetic abnormalities of band 11q23 have been found in more than 50% of infant leukemias regardless of the phenotype. Using probes for the MLL gene at 11q23, MLL rearrangements have been identified in 70-80% of all infant leukemias including virtually all of the cases with 11q23 translocations, as well as cases with apparently normal karyotypes. We reviewed the chromosomal pattern of 26 cases of infant leukemias (12 ALL, 12 AML, two AUL). Eleven had 11q23 translocations, five had other abnormalities, and 10 had a normal karyotype. To determine whether 11q23/MLL rearrangements were present in the leukemia cells of patients with a normal karyotype, we performed FISH and molecular studies of eight of these patients who had adequate material. Three were found to have 11q23/MLL abnormalities, two of them detected by FISH; one ALL case had a t(11;19) (q23;p13.3), and one AML case had a t(11;19) (q23;p13.1). Retrospective review confirmed the presence of the t(11;19) in a small percentage of poor quality metaphase cells in both cases. A rearrangement of the MLL gene was detected by Southern blot analysis of leukemic cells from a third patient with ALL; one cell with a deletion of 11q23 was found on karyotypic review. Therefore, in our series the actual incidence of 11q23 abnormalities in infant leukemias was 54% (14/26): 67% in ALL (8/12) and 50% in AML (6/12). Our findings suggest that most infant leukemias with apparently normal karyotypes that have a molecular rearrangement of the MLL gene are undetected subtle translocations.(ABSTRACT TRUNCATED AT 250 WORDS)
无论表型如何，超过50%的婴儿白血病中都发现了11q23带的细胞遗传学异常。使用位于11q23的MLL基因探针，在所有婴儿白血病的70%-80%中鉴定出MLL重排，包括几乎所有11q23易位的病例以及核型明显正常的病例。我们回顾了26例婴儿白血病（12例急性淋巴细胞白血病、12例急性髓细胞白血病、2例急性未分化白血病）的染色体模式。11例有11q23易位，5例有其他异常，10例核型正常。为了确定核型正常的患者白血病细胞中是否存在11q23/MLL重排，我们对其中8例有足够样本的患者进行了荧光原位杂交（FISH）和分子研究。发现3例有11q23/MLL异常，其中2例通过FISH检测到；1例急性淋巴细胞白血病病例有t(11;19)(q23;p13.3)，1例急性髓细胞白血病病例有t(11;19)(q23;p13.1)。回顾性分析证实，这两例病例中均有一小部分质量较差的中期细胞存在t(11;19)。通过对第三例急性淋巴细胞白血病患者白血病细胞的Southern印迹分析检测到MLL基因重排；核型检查发现1例细胞有11q23缺失。因此，在我们的系列研究中，婴儿白血病中11q23异常的实际发生率为54%（14/26）：急性淋巴细胞白血病中为67%（8/12），急性髓细胞白血病中为50%（6/12）。我们的研究结果表明，大多数核型明显正常但MLL基因发生分子重排的婴儿白血病是未被检测到的细微易位。（摘要截短于250字）
