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We report the occurrence of a BCR-JAK2 fusion gene in a case of acute myeloid leukemia (AML) resulting from a t(9;22)(p24;q11) translocation as the sole cytogenetic abnormality. The BCR-JAK2 fusion gene has the same breakpoint in BCR as is found in the BCR/ABL p210. The chimeric gene is the result of a reciprocal translocation between chromosomes 9 and 22, which implies a double break on chromosome 9; this has allowed generating an in-frame fusion transcript. Previously, BCR-JAK2 rearrangement was observed in a single case with atypical chronic myelogenous leukemia (CML), but in that case the breakpoint in the BCR was different., ((c) 2008 Elsevier Inc.)

Chromosomal translocations involving the 12q14 band are rarely detected in hematological disorders, and are usually correlated with HMGA2 gene expression. HMGA2 is highly expressed during embryonic cell growth and differentiation, and regulates transcription and chromatin organization, but is rarely detectable in adult tissues. We describe a case of polycythemia vera with a t(12;21)(q14;q22). The 12q14 breakpoint was characterized by fluorescence in situ hybridization analysis using the bacterial artificial chromosome RP11-366L20 containing 3' sequences of the HMGA2 gene. Qualitative and quantitative polymerase chain reaction showed the presence of high levels of HMGA2 gene expression, which were temporarily reduced with hydroxyurea therapy. The present case confirms that involvement of the 12q14 band may be associated with HMGA2 overexpression in chronic Philadelphia chromosome-negative myeloproliferative disease, regardless of the partner chromosome involved in the translocation. Such overexpression may contribute to the pathogenesis of the disease, which otherwise of itself shows a favorable and stable course.

The cytogenetic studies and molecular evaluation of a Philadelphia chromosome negative chronic myelogenous leukemia patient with trisomy 21 (100% metaphases) and trisomy 9 (50% metaphases) at diagnosis are described. Fluorescence in situ hybridization revealed an atypical location of the BCR/ABL fusion signal on 9q, which was duplicated in cells with trisomy 9 simulating a double Ph. The patient was successfully treated with Glivec (also known as Gleevec; Novartis, Basel, Switzerland) and achieved complete hematological and cytogenetic response as well as a reduction of BCR/ABL transcripts detected by real-time quantitative PCR.

Cytogenetic analysis of 72 consecutive de novo myelodysplastic syndrome patients revealed monosomy 7 in 12 cases. In 4 of these cases, the -7 was the only abnormality, whereas the remaining 8 cases showed additional chromosomal aberrations. Fluorescence in situ hybridization (FISH) utilizing chromosome 7 alpha-satellite and painting probes and other specific probes, when necessary, provided evidence of unusual and unsuspected structural rearrangements involving chromosome 7. FISH analysis showed that the small fragment found in one patient and the ring found in each of two other patients were chromosome 7-derived rings. FISH also revealed the insertion of chromosome 7 sequences into autosomes in three other patients and unusual translocations in the remaining two patients. By comparing the results obtained by using banding techniques to those obtained by using the FISH technique, we deduced the involvement of chromosome 7 with partial deletion of the short arm in all eight examined patients. Our study confirms the ability of FISH to detect chromosomal aberrations that would otherwise not be identified and the tendency of chromosome 7 to be involved in many different rearrangements. From a clinical point of view, we confirm that patients affected by myelodysplastic syndromes with complex karyotypes involving chromosome 7 do not respond to treatment and have a poor prognosis.

Correct diagnosis of acute promyelocytic leukemia (APL) requires proof of the translocation (15;17)(q24;q11), which appears to be absolutely specific for this particular type of myeloid disorder. We studied the karyotypes of 29 consecutive APL patients at diagnosis: in 5 of them banding techniques failed to detect the t(15;17). In these seemingly cytogenetically negative cases, fluorescence in situ hybridization (FISH) with a chromosome 17 painting probe detected a high percentage of mitoses with 3 hybridization signals: one derived from the intact chromosome 17, and 2 from the rearranged chromosomes 15 and 17. Trisomy 8 (+8) as a secondary chromosomal abnormality was observed in 8 cases (27.5%), confirming that the t(15;17) favors the acquisition of an extra chromosome 8. One of these 8 cases showed a marker that was interpreted by FISH analysis as der(8) with duplication of a segment of the long arm carrying the c-MYC allele. Clinical features of patients with t(15;17) and +8 were no different from patients with t(15;17) alone. The usefulness of FISH to standard banding techniques in the detection of specific structural and/or numerical chromosomal abnormalities is confirmed in this report.

Previous reports suggested a correlation between the deletion of the terminal region of the short arm of a chromosome 17 and the appearance of dysgranulopoiesis in myeloproliferative disorders. Using the dual-color fluorescence in situ hybridization technique we analyzed the bone marrow and peripheral blood cells of a Philadelphia chromosome-positive chronic myeloid leukemia (CML) patient showing at the onset of transformation into blastic crisis both metaphases with the i(17q) as well as granulocytes without nuclear segmentation. This phenomenon is defined as pseudo-Pelger-Huët anomaly. Using two probes, one specific for 17p and one for 17q, we determined the presence or absence of the i(17q) in both metaphase and interphase cells. Moreover, we observed that all cells with a polysegmented nucleus typical of mature granulocytes did not have i(17q) but had two normal chromosomes 17. This observation confirmed the correlation between 17p deletion and the appearance of pseudo-Pelger anomaly. This finding may also be useful from a clinical point of view: the appearance of pseudo-Pelger cells in CML indicates that 17p deletion actually occurred. This event implies a negative prognosis.

Using the fluorescence in situ hybridization technique, we analyzed a ring chromosome that appeared as a karyotype evolution in a patient affected by refractory anemia with excess of blasts in transformation. Metaphases hybridized with a chromosome-8-specific centromeric probe indicated that the ring retained the centromere of chromosome 8. Successively, utilizing a probe specific for all human telomeres, we observed that the ring lost telomeric sequences. This study demonstrated that the formation of a ring chromosome in hematologic disorders can cause loss of genetic material not revealed by banding techniques and therefore providing further proof of the advantages of molecular cytogenetic techniques.

Examining a bone marrow (BM) karyotype of a patient with a refractory anemia with excess of blasts (RAEB), we detected a clone with an unbalanced translocation(1;17), resulting in monosomy of 17p and trisomy of 1q. Using fluorescence in situ hybridization (FISH) technique with alpha-satellite DNA probes specific for chromosomes 1 and 17, we observed that the chromosome derived from the translocation shows hybridization signals for both the centromeres of chromosomes 1 and 17. This finding suggests that the breakpoints of the two autosomes involved in the rearrangement occurred in the primary constriction. The case confirms the ability of ISH analysis to detect structural rearrangements in cancer cytogenetics.

This work contains a cytogenetic analysis of 507 consecutive CML patients examined at diagnosis before any therapeutic treatment. Philadelphia chromosome translocations different from the standard t(9;22)(q34;q11) were observed in 28 patients (5.5%). Structural chromosomal abnormalities apparently unrelated to the Ph were found in six patients carrying variant Ph (6 of 28 = 21.4%) and in three patients carrying standard Ph translocations (3 of 472 = 0.6%). This finding confirms that structural abnormalities other than Ph are a rare event at diagnosis but that they occur with significantly different frequencies between the variant and standard Ph translocations, indicating that causes favoring the variant Ph formation may promote additional non-lethal DNA breakpoints.

We examined bone marrow (BM) cells from 6 Philadelphia chromosome positive (Ph+) chronic myeloid leukemia (CML) patients in advanced phase of the disease using conventional cytogenetic techniques and fluorescence in situ hybridization (FISH) for detection of an extra chromosome 8. All patients showed mosaicism for trisomy 8 as a secondary chromosome abnormality. For FISH, we used the D8Z5 probe specific for the centromeric region of chromosome 8 and analyzed 300 interphase nuclei and a variable number of mitoses for each patient. The percentages of metaphases carrying trisomy 8 were similar with both techniques, whereas the percentage of interphase nuclei showing three hybridization spots indicative of trisomy 8 was significantly lower than that in metaphases. This finding suggests that cells with a supernumerary chromosome 8 may have a cell cycle time shorter than that of disomic cells.

In 420 Philadelphia positive (Ph+) chronic myeloid leukemia (CML) patients karyotyped at diagnosis in our laboratory, 26 Ph variants (6.2%) were observed. Twelve of them are reported. Five cases are "simple" variants without detectable involvement of band 9q34, and seven are "complex," since a third chromosomal band is involved in the Ph formation. Two translocations [t(7;22)(q36;q11) and t(9;22;12)(q34;q11;q11)] are reported for the first time. Six cases were characterized molecularly, and bcr-abl rearrangement was demonstrated, confirming involvement of 9q34 band also in the cases in which chromosomes 9 appear cytogenically normal. Chimeric mRNAs in which M-BCR exon 3 is joined to abl exon 2 (type b3-a2) were detected in four of six cases; one case showed a DNA breakpoint in zone III, which may also give rise to the same transcript. In one case, mRNA junction was b2-a2. The frequency of the b3-a2 junction occurs more frequently in CML patients with a Ph variant than in patients with the standard translocation, suggesting a preferential correlation between this type of transcript and the involvement of other chromosomes in Ph formation.

We present the cytogenetic pattern of a leukemic infant with Diamond-Blackfan anemia (DBA). The karyotype was characterized by clonal evolution involving consecutive gains of chromosome 21 up to pentasomy. No chromosomal changes were present in normal lymphocytes. Such a karyotype evolution has been described in some cases of acute leukemia associated with Down Syndrome, but rarely in non-Down cases.

We present the case of a 4-day-old boy with acute lymphoblastic leukemia showing at onset a karyotype 46,XY,t(4;11)(q21;q23). At relapse an additional change, add(2), was present. Molecular analysis showed the same immunoglobulin rearrangement both at onset and at relapse, but immunohistochemical analysis revealed some cells having myeloid features. A continuous cell line derived from the leukemic blasts of the patient presented typical monoblastic features.

Sixty-eight patients affected by Philadelphia chromosome (Ph) positive chronic myelogenous leukemia (CML) underwent allogeneic bone marrow transplantation (BMT) and were successfully studied from a cytogenetic point of view, before and after the BMT. Nineteen had evidence of cytogenetic and clinical relapse. Cytogenetic analyses of 14 patients who, after the relapse, showed progression to the accelerated or blastic phase of the disease, are presented. Five of these cases had only the Ph chromosome without karyotype evolution; in one case Ph duplication without other anomalies was detected, while in the remaining eight cases cytogenetic analysis showed apparently random clonal structural abnormalities (translocations, inversions, deletions, and marker formations). Therefore, the classical "non-random" abnormalities (+8, i(17q), +Ph, +19, +21) were not as common as in conventionally treated Ph+ CML. From our data, karyotype evolution during advanced phases in Ph+ CML patients after BMT differs from the evolution seen in conventionally treated patients, by the presence of numerous structural unusual abnormalities, possibly related to radiochemotherapy conditioning to BMT. Therefore, BMT treatment is not always able to eradicate the Ph+ clone but can reduce the incidence of the formation and/or expansion of Ph+ clones with additional non-random abnormalities.

Three Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL) patients showed rearrangement of the short arm of the chromosome 9 involved in Ph formation. At diagnosis, blast cells were morphologically L2 and phenotypically B-cell precursors, as shown by common ALL antigen (CALLA), B1, B4 and HLA-DR positivity. Cytogenetically, they had in common the presence of cells with normal karyotypes, the Ph, involvement of band 9p13----p21, and loss of region 9p13----9pter. In our experience, involvement of the p arm of the derivative chromosome 9 in Ph+ leukemias is a very rare event found in ALLs only.

Between 1979 and 1988, 86 patients with clinical and laboratory findings consistent with essential thrombocythemia (ET) were karyotyped at diagnosis. Four patients showed a Philadelphia chromosome and underwent myeloid blastic crisis 2.5-4.5 years later, strongly suggesting a diagnosis of chronic myeloid leukemia. A partial deletion of 13q was seen in another case evolving to leukemia a few months later. Five cases, with normal karyotypes at diagnosis, developed acute transformation after more than 5 years of chronic phase. Four of them showed unusual clonal karyotype abnormalities involving different chromosomal regions. The numerical abnormalities found were trisomy 22 in one case, and trisomy 8 and 19 in another, while structural changes included partial deletion of 5p, partial deletion of 6q, pericentric inversion of chromosome 12, and partial deletion of 20q. These abnormalities have not been previously reported in ET. This investigation confirms the absence of a specific cytogenetic marker for ET, and the infrequent transformation to acute leukemia, often with chromosomal clonal disorders.