Antonio Spadano

Complex translocations of the Ph chromosome and Ph negative CML arise from similar mechanisms, as evidenced by FISH analysis

The authors report on 13 patients with chronic myeloid leukemia (CML) studied by serial karyotyping and fluorescence in situ hybridization (FISH) of their bone marrow cells. Ten patients had complex translocations of the Ph chromosome while the remaining three were Ph negative. FISH analysis revealed in all 13 patients the translocation of the ABL protooncogene into chromosome 22 at band q11. Moreover, in all complex translocations but one, FISH with a chromosome 22 painting probe demonstrated on one chromosome 9 at band q34 the presence of material from chromosome 22, in addition to signals on the third chromosome involved in complex changes. Therefore, in this study complex translocations appeared as secondary changes resulting from two consecutive translocations with a total of at least four breaks. The first translocation gave rise to the standard t(9;22)(q34;q11). The second one included a break distal to the original breakpoint at band 9q34 and another one on a third chromosome. Furthermore FISH using S1 and S15 probes, mapped at band 22q11.2 or 22q12, gave evidence that in complex translocations the secondary breakpoint on der(9) was in the translocated segment 22q11-qter between bands q11 and q12. FISH analysis also disclosed the presence of material from chromosome 22 on one chromosome 9 in the three patients with Ph negative CML, demonstrating that in these cases a retranslocation between chromosomes 9q+ and 22q- had occurred. Consequently, the four-break mechanism could also be invoked for the three Ph negative CML patients.

p53 loss and point mutations are associated with suppression of apoptosis and progression of CML into myeloid blastic crisis

A longitudinal investigation using fluorescence in situ hybridization (FISH) analysis, PCR-SSCP, and in situ detection of apoptosis by the terminal deoxynucleotidyl Transferase (TdT) method was carried out on 13 chronic myelogenous leukemia (CML) patients to study the p53 gene behavior and the apoptotic process during the course of the disease. At diagnosis, FISH showed no loss of the p53 gene on interphase nuclei, and no point mutation was detected by polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) and sequencing. During the disease course, FISH analysis showed a significative loss of allele (LOA) rate for the p53 gene in eight patients that in seven cases was associated with a suppression of apoptotic process and the progressive expansion of the p53+/p53- clone. DNA sequencing showed in two of these eight patients a point mutation on the other allele, consisting in the formation of a stop codon in one case, and in a frameshift mutation in the other. Six patients had a myeloid blastic crisis (BC), five a lymphoid BC, and the other two an erythroid and an undifferentiated BC, respectively. All patients with myeloid BC and the one with undifferentiated BC disclosed a progressive expansion of the clone with p53 loss that was associated with a significant reduction in apoptosis. On the contrary in the 5 patients with lymphoid BC no significant p53 LOA rate was observed during the course of the disease. In these patients apoptotic process also persisted in the acute phase although in a lower rate as compared to CP.

Chromosome changes in 19 patients with Waldenström's macroglobulinemia

We report on 19 patients with Waldenströms macroglobulinemia (WM) who were studied cytogenetically at the onset and during progression of the disease. We found a high frequency of chromosome changes confirming the claim of other authors that, during progression of the disease, a large number of residual neoplastic cells, insensitive to conventional chemotherapy, persist. In turn, this may be the cause of the difficulty of inducing remission (21% of cases) and of the short survival (mean, 35 months). In our experience it is difficult to identify the primary chromosome abnormalities because of the late clinical stage at which the chromosomes were examined. However, changes involving chromosomes #10, #11, and #12 may be unfavorable events in patients with WM.

Cytogenetic survey of 80 patients with acute nonlymphocytic leukemia

The authors report a cytogenetic survey of 80 patients with acute nonlymphocytic leukemia. The prognostic value of chromosome aberrations has been evaluated with three methods. The first one showed that patients with NN or AN bone marrow cellularity have a significantly better prognosis than those with AA cellularity; the second method confirmed the relatively good prognosis for patients with t(8;21) and abnormal 16 and a poor one for those with rearrangements of chromosomes 5 and/or 7. The authors also noted, surprisingly, that patients with hyperdiploidy had a significantly poorer prognosis than those with hypodiploidy and especially pseudodiploidy. The third method showed that patients with very complex karyotypes and a worse outcome than those with simple changes. Finally, they discuss the prognostic value of unusual and/or undeciphered chromosome changes detected in 18 patients, with a mean survival of 9.6 months, showing that these changes have a negative prognostic significance.

Chromosome 11 rearrangements and specific MLL amplification revealed by spectral karyotyping in a patient with refractory anaemia with excess of blasts (RAEB).

Summary. A patient with refractory anaemia with excess of blasts (RAEB) had a complex karyotype with multiple markers. Spectral karyotyping (SKY) showed rearrangements including three different der(11), containing a very high number of MLL gene copies, shown by fluorescence in situ hybridization (FISH) analysis. Fibre‐FISH experiments disclosed the presence of chromatin fibres with multiple MLL copies with a head‐to‐tail pattern. Apparently, no other region flanking the MLL site was present in the three der(11). MLL amplification was confirmed by the reverse transcription polymerase chain reaction (RT‐PCR). The patient died 6u2003months after diagnosis, supporting the severe prognosis of sole MLL amplification.

Leukemic evolution in three patients with myelodysplastic syndrome and unusual chromosome changes

The authors describe three patients with myelodysplastic syndrome without a history of exposure to chemical agents and who showed many chromosome rearrangements not previously reported in this hematologic disorder, and a rapid outcome of the disease. The authors discuss the significance of the chromosome changes, suggesting, in agreement with others, that patients with complex rearrangements have a poor prognosis.