BCR/ABL fusion located on chromosome 9 in chronic myeloid leukemia with a masked Ph chromosome

A reciprocal translocation, t(10; 22) (q22; q11), resulting in a masked Ph chromosome was identified in a patient diagnosed with chronic myeloid leukemia (CML). Both homologs of chromosome 9 were of the normal pattern. Two signals for the ABL probe, both of them hybridized to chromosome 9, were demonstrated via fluorescence in situ hybridization (FISH). Furthermore, cohybridization with two differently labeled BCR/ABL translocation DNA probes indicated a BCR/ABL fusion apparently located on 9q34. Molecular studies revealed a rearrangement of the BCR region and expression of a chimeric BCR/ABL mRNA of CML configuration. These findings indicate that the BCR/ABL fusion resulted from an unusual relocation of the BCR gene from its normal position on 22ql I to 9q34 adjacent to the ABL gene.     

荧光原位杂交检测慢性粒细胞白血病的染色体畸变

目的 检测费城染色体（Ｐｈｉｌａｄｅｌｐｈｉａ ｃｈｒｏｍｏｓｏｍｅ，Ｐｈ染色体）阴性，变异型Ｐｈ染色体及伴有其它染色体异常的慢性粒细胞白血病（ｃｈｒｏｎｉｃ ｍｙｅｌｏｉｄ ｌｅｕｋｅｍｉａ，ＣＭＬ）的ｂｃｒ／ａｂｌ融合基因。方法 双色荧光原位杂交技术，检测伴有８种不同的骨髓细胞染色体畸变ＣＭＬ患者的ｂｃｌ／ａｂｌ融合基因。结果 ３例变异型Ｐｈ和７例有标准型Ｐｈ的ＣＭＬ患者均为ｂｃｒ／ａｂｌ融合     

The clinical and cytogenetic significance of C-banding on chromosome #9 in patients with Ph1-positive chronic myeloid leukemia

The C-band polymorphism of chromosome #9 in 18 patients with chronic myeloid leukemia (CML) with a Philadelphia chromosome (Ph1) translocation between chromosomes #9 and #22 was examined using C- and Q-banding techniques on the same metaphases and the classification proposed by Patil and Lubs [1]. The C-band polymorphism of chromosome #9 in CML was found not to differ in leukemic cells with the Ph1 and phytohemagglutinin-stimulated lymphocytes without the Ph1 and to have a clonal origin, i.e., to arise from a single cell in which the Ph1 translocation has taken place. A comparison of the C-band polymorphism of chromosome #9, survival after diagnosis of the disease, and abnormal chromosomes in addition to the Ph1 indicates some interesting aspects. Patients with the smallest C-band (level 1) on chromosome #9 not involved in the Ph1 translocation and with a relatively large C-band (level 2) on chromosome #9 with the Ph1 translocation (C9-1,2) tend to have no clonal evolution and short survival after diagnosis of the disease. On the other hand, patients with other types of C-band patterns tend to have evidence of clonal evolution and long survival. This study suggests that the C-banding pattern in Ph1-positive CML might be utilized as a prognostic parameter in the disease and that the C-segment might have biological activity.     

Molecular cytogenetic characterization of a complex rearrangement involving chromosomes 9 and 22 in a case of Ph-negative chronic myeloid leukemia

The "golden path", produced by the Human Genome Project effort, is composed of a collection of overlapping and fully sequenced BAC/PAC clones covering almost completely the human genome. These clones can be advantageously exploited as fluorescence in situ hybridization (FISH) probes for the characterization of rearrangements frequently found in tumors. Breakpoint characterization can be further refined by generating additional smaller FISH probes through LONG-PCR amplification of specific DNA segments, 5-10 kb in size, using appropriate BAC/PAC probes as template. We report here an example of this approach that has been used to characterize a complex Ph-negative chronic myeloid leukemia (CML Ph-) case in which the BCR/ABL fusion gene was found located on chromosome 9.     

BCR/ABL fusion gene detected on 9q34 by fluorescence in situ hybridization in an acute leukemia with two BCR/ABL positive clones, one Ph-negative and one Ph-positive.

We report cytogenetic, fluorescence in situ hybridization (FISH), and molecular analyses in the first reported case of an acute leukemia with two BCR-positive clones: one cell Ph-positive and all others Ph-negative. A BCR/ABL fusion gene on 9q34 was detected only with a BCR/ABL dual color translocation probe. These FISH interphase signals must be confirmed on a metaphase to avoid an erroneous interpretation. This observation appears to indicate a 2-step mechanism for this aberrant fusion gene localization: first, a classical t(9;22), and then the transfer of the fusion gene formed on chromosome 22 to chromosome 9 by a second translocation between the long arms of the derivative chromosomes 9q+ and 22q-, masking the first chromosome exchange.     

A cytogenetic and molecular analysis of five variant Philadelphia translocations in chronic myeloid leukemia

Three patients had complex translocations involving 9q34, 22q11, and a third chromosome (Xq11, 7q11.2, or 15q11.2). Two patients had apparently simple variant Philadelphia (Ph) translocations, t(19;22) and t(11;22), with no obvious involvement of chromosome 9, and the Ph was masked in the t(11;22). In situ hybridization studies showed transposition of the abl gene from chromosome 9q34 to the breakpoint cluster region (bcr) of chromosome 22 in all five patients; this was confirmed by rearrangements of the bcr gene in leukemic DNA. In situ hybridization also showed that the bcr-3' and c-sis probes consistently translocated to recipient chromosomes X, 1, 7, 11, and 15, whereas IgC lambda remained on chromosome 22q. These results confirm that association of abl and bcr is a consistent feature of chronic myeloid leukemia irrespective of the cytogenetic presentation and support the conclusion of Hagemeijer that all simple variant Ph translocations are, in fact, complex and involve at least three chromosomes.     

慢性粒细胞白血病细胞遗传学改变临床分析

目的探讨慢性粒性细胞白血病（CML）的细胞遗传学特点及意义。方法采用24h短期培养法制备骨髓染色体,应用G显带技术进行染色体核型分析。结果194例CML患者中,166例ph＋（占85．57％）,28例ph-（占14．43％）,其中158例具有典型易位,8例复杂变异易位,98例出现其他附加染色体异常,主要为：-22,＋8、-21、-11、-10、-14和-20等。结论CML患者进行细胞学研究对疾病的诊断、治疗和判断预后具有重要意义。     

A Ph-negative chronic myeloid leukemia with a complex BCR/ABL rearrangement and a t(6;9)(p21;q34.1)

Chronic myeloid leukemia (CML) is a clonal malignant disorder of a pluripotent hematopoetic stem cell characterized by the presence of the Philadelphia (Ph) chromosome in more than 90% of patients. Cryptic or "masked" BCR/ABL gene rearrangements may be found in cases with a normal karyotype and in cases with the complex karyotype, in which typical t(9;22) is not visible at the microscopic level. Those rearrangements can now be detected by fluorescence in situ hybridization. Here, we report on a novel and complex Ph chromosome-negative CML case with a t(6;9)(p21;q34.1) in which the BCR/ABL fusion gene is located at 6p21.     

Translocation 3;21 in Philadelphia chromosome positive chronic myeloid leukemia at diagnosis

We describe a further case of Philadelphia chromosome-positive chronic myeloid leukemia with a t(3;21)(q26.2;q22) present in the chronic phase. Blastic transformation occurred 8 months after presentation. The presence of the t(3;21) may indicate a poor prognosis.     

Clinical implications of fluorescence in situ hybridization analysis in 13 chronic myeloid leukemia cases: Ph-negative and variant Ph-positive.

Thirteen chronic myeloid leukemia (CML) patients, 10 with variant Philadelphia (Ph) translocations and 3 Ph negative cases, were analyzed by fluorescence in situ hybridization (FISH) with the use of BCR and ABL cosmid probes and a chromosome 22 painting probe. In the variant Ph translocations, the BCR-ABL fusion gene was located on the Ph chromosome; in 1 CML Ph-negative patient, the BCR-ABL fusion gene was located on the Ph chromosome; and, in 2 patients, it was located on chromosome 9. The chromosome 22 painting probe was detected on the third-party chromosome of the variant translocation, and in none of the variant translocations was there any detectable signal on chromosome 9. In CML patients with clonal evolution of a simple Ph, a signal of the chromosome 22 painting probe was detected on the der(9) of the Ph translocation. It was concluded that the variant Ph translocations evolved simultaneously in a three-way rearrangement. The clinical parameters of the 13 patients were similar to those of a large group of CML patients with a simple Ph translocation. It is suggested that, to determine the prognosis of CML patients with a complex karyotype, FISH analysis with a chromosome 22 painting probe be performed.     

慢性粒细胞白血病患者染色体检查及预后意义探讨

目的探讨慢性粒细胞白血病(CML)患者染色体变化的有关特点及预后意义.方法染色体制备采用骨髓细胞短期培养法,应用G、R显带技术对85例CML患者的骨髓细胞进行遗传学分析.结果 85例CML患者中,78例检出典型Ph染色体,占91.76%,3例为变异Ph易位,占3.53%,4例Ph染色体阴性,占4.71%,10例核型呈嵌合状态,13例出现附加染色体异常,主要为 8,i(7), Ph, 22, 12等,其中9例为加速和急变期患者,占64.29%.结论 CML是一种高度异质性疾病,非随机的附加染色体异常与患者临床分期高度相关.CML患者进行染色体分析对于疾病的诊断及鉴别、指导临床治疗、判断预后具有重要意义.     

荧光原位杂交技术在诊断变异Ph易位及Ph(一)慢性髓细胞白血病中的应用

目的 探讨荧光原位杂交(fluorescence in situ hybridization,FISH)技术在诊断变异Ph易位及Ph(-)慢性髓细胞白血病(chronic myelocytic leukemia,CML)中的应用价值.方法 应用常规R显带方法,对9例伴有变异Ph易位和2例Ph(-)CML患者采用双色双融合bcr/abl探针进行FISH检测.结果 9例变异Ph易位CML患者异常核型除涉及9和22号染色体外,还涉及1、3、5、12、13、15、17、21号染色体,且部分类型为重现性异常,FISH结果均为阳性,信号特征为2R2G1Y;2例Ph(-)CML患者核型正常,FISH结果阳性,信号特征分别为1R1G2Y和1R1G1Y.结论 FISH技术对伴有变异Ph易位及Ph(-)CML患者的诊断更具有优势,可根据阳性细胞信号特征分析其异常核型,判断标记基因异常改变情况,是常规染色体显带分析的有益补充.     

Secondary chromosome changes in chronic myeloid leukemia: Relation to treatment

Thirty four patients with Philadelphia (Ph¹) chromosome positive chronic myeloid leukemia with clonal bone marrow chromosome aberrations in addition to the Ph¹, were divided into two groups: 1) 23 patients treated with busulfan only during the chronic phase, and 2) 11 patients treated with intensive chemotherapeutic schedules during the chronic phase. In all the material studied, about 85% of the patients showed at least one of three particular changes: +8, iso(17q), and/or +Ph¹. The frequency of each of these three aberrations was similar in the two groups. Additional structural changes of a clonal nature were, however, seen in only 3 of the 23 patients treated with busulfan only, but were present in 5 of the 11 patients treated with intensive chemotherapy. The results indicate that intensive chemotherapy may produce new stable abnormal clones in patients with leukemia. Furthermore, chromosome 1 was involved in aberrations in all 5 patients with structural changes undergoing intensive chemotherapy, but in no patient treated with busulfan only. The 11 patients treated with intensive chemotherapy were studied in Italy, whereas 20 of the 23 patients treated with busulfan only were studied in Sweden. The possibility that the differences recorded between the two groups may be geographical in nature rather than induced by treatment cannot be excluded.     

Cryptic terminal rearrangement of chromosome 22q13.32 detected by FISH in two unrelated patients.

Two unrelated patients with cryptic subtelomeric deletions of 22q13.3 were identified using FISH with the commercially available Oncor probe, D22S39. Proband 1 was found to have a derivative chromosome 22 resulting from the unbalanced segregation of a t(1;22)(q44;q13.32) in her mother. Additional FISH analysis of proband 1 and her mother placed the breakpoint on chromosome 22 in this family proximal to D22S55 and D22S39 and distal to D22S45. We have mapped D22S39 to within 170 kb of D22S21 using pulsed field gel electrophoresis. D22S21 is genetically mapped between D22S55 and D22S45. These data indicate that the deletion in proband 1 is smaller than in eight of nine reported del(22)(q13.3) patients. Probands 1 and 2 share features of hypotonia, developmental delay, and expressive language delay, also seen in previously reported del(22)(q13.3) patients, although proband 1 appears to be more mildly affected. Proband 1 is also trisomic for the region 1q44-->qter. This very small duplication has been previously reported only once and the patient had idiopathic mental retardation. This is the first report where 22q13.3 terminal deletion patients have been identified through the use of FISH, and the first report of a deletion of this region occurring because of missegregation of a parental balanced cryptic translocation. We feel that investigation of the frequency of del(22)(q13.3) in the idiopathic mentally retarded population is warranted and may be aided by the ability to use a commercially available probe (D22S39), which is already currently in use in a large number of cytogenetic laboratories.     

Translocation of c-abl to "masked" Ph in chronic myeloid leukemia

In two patients with chronic myeloid leukemia (CML), the nature of the chromosomal rearrangement giving rise to "masked" Ph has been studied by in situ hybridization of human c-abl sequences. The c-abl probes hybridized to the 22q11 region of the "masked" Ph, demonstrating that translocation of sequences from 9q34 to the Ph did occur exactly as in standard Ph or in other types of variants previously studied. These results provide additional evidence for the occurrence of a constant molecular rearrangement in Ph-positive CML.