Complex Ph Translocation Research Articles

Complex three-way Philadelphia translocation t(6;9;22) (p23;q34;q11.2) along with unusual t(1;4): A chronic myeloid leukemia case report

Chronic myeloid leukemia (CML) is a myeloproliferative disorder and genetically characterized by the presence of the Philadelphia (Ph) chromosome, resulting from a balanced reciprocal translocation between chromosome 9 and 22 at bands 9q34 and 22q11.2 [t(9;22)(q34;q11.2)]. In the formation of the Ph chromosome, the specific region of the ABL oncogene is transposed from 9q34 to the specific region of the BCR gene on chromosome 22 to form a fusion gene BCR‑ABL, which encodes a constitutively active protein, with tyrosine kinase activity. Vast majority of CML patients show classical Ph translocation, t(9;22) and 5–10% of cases are observed with variant Ph translocation. In variant Ph translocation, generally, the third chromosome involved with chromosome 9 and 22. The segment of the third chromosome usually translocates to the chromosome 9 at band 9q34. The formation of variant or complex Ph translocation is controversial topic. A wide array of additional chromosome involved in translocation with the t(9;22) has been described previously in CML patients. In this report, we present a unique and complex Ph translocation involving three chromosomes (6;9;22) in a 25-year-old female 66who was clinically diagnosed as CML. Chromosome analysis using 24 h and 48 h unstimulated culture with GTG-banding was performed according to standard protocol. A total of 20 metaphases analyzed from the bone marrow culture of the patient and karyotyping was performed on the basis of International System for Human Cytogenetic Nomenclature (2016). The FISH analysis was performed according to the standard protocol from sample for confirmation of BCR/ABL gene using dual color fusion FISH probe (Zytovision Probe). All cell’s images were captured using Olympus fluorescent microscope BX-61 equipped with a CCD camera and analyzed using Bioview FISH software.

Variant Philadelphia translocations with different breakpoints in six chronic myeloid leukemia patients.

The Philadelphia (Ph) chromosome, consisting of the t(9;22)(q34;q11) translocation, is observed in ~90% of patients with chronic myeloid leukemia (CML). Variant Ph translocations are observed in 5%-10% of CML patients. In variant translocations 3 and possibly more chromosomes are involved. Herein we report 6 CML patients with variant Ph translocations. Bone marrow samples were examined using conventional cytogenetic meth ods. Fluorescence in situ hybridization (FISH) with whole-chromosome paints and BCR-ABL 1D probes were used to confirm and/or complement the findings, and identify rearrangements beyond the resolution of conventional cytogenetic methods. Variant Ph translocations in the 6 patients were as follows: t(7;22)(p22;q11), t(9;22;15)(q34;q11;q22), t(15;22)(p11;q11), t(1;9;22;3)(q24;q34;q11;q21), t(12;22)(p13;q11), and t(4;8;9;22)(q11;q13;q34;q11). Among the patients, 3 had simple and 3 had complex variant Ph translocations. Two of the presented cases had variant Ph chromosomes not previously described, 1 of which had a new complex Ph translocation involving chromosomes 1, 3, 9, 22, and t(1;9;22;3)(q24;q34;q11;q21) apart from a clone with a classical Ph, and the other case had variant Ph translocation with chromosomes 4, 8, 9, and 22, and t(4;8;9;22)(q11;q13;q34;q11) full complex translocation. Number of studies reported that some patients with variant Ph translocation were poor responders to imatinib. All of our patients with variant Ph translocations had suboptimal responses to imatinib, denoting a poor prognosis also. Variant Ph translocations may be important as they are associated with prognosis and therapy for CML patients.

Low megakaryocyte ploidy in Ph-positive chronic myelogenous leukemia measured by flow cytometry.

In chronic myeloproliferative disorders, the megakaryocytes differ in size and maturation compared with those of healthy individuals. In the present study, by using a 2-color flow cytometry technique, we determined the frequency of bone marrow megakaryocytes in different ploidy classes in 13 newly diagnosed and untreated patients with Philadelphia chromosome (Ph)-positive chronic myelogenous leukemia (CML) and in 12 healthy volunteers. The results showed a significant difference in megakaryocyte ploidy distributions between these 2 study groups. On the average, patients with CML had 59% of their megakaryocytes in ploidy classes 2N to 8N; in contrast, the healthy volunteers had only 22% of their megakaryocytes in classes 2N to 8N. Two patients with complex Ph translocation and 2 patients with a small clone with a chromosome abnormality in addition to Ph had the same ploidy distribution as those with only Ph translocation. The platelet count did not correlate with the megakaryocyte mean ploidy.

New variant Ph translocation in chronic myeloid leukemia: t(Y;22)(p11;q11)

A 4-year-old boy with chronic myeloid leukemia (CML) was shown to have a variant Ph t(Y;22)(p11;q11). To our knowledge, this is the first report of a variant Ph translocation involving Y. Molecular analysis showed that the breakpoint on chromosome 22 is in the breakpoint cluster region (bcr), typical of CML with the classic t(9;22), suggesting that it might be a complex Ph translocation with the involvement of 9q34.

Philadelphia chromosome positive B‐cell type malignant lymphoma expressing an aberrant 190 kDa bcr‐abl protein

The Philadelphia (Ph) chromosome translocation, t(9:22) (q34;q11) is found in some acute lymphoid leukaemias (ALL) and acute myeloid leukaemias (AML). Although cytogenetically all pH chromosomes appear similar, the 22q11 breakpoints found in acute leukaemias are of two kinds, those within the major breakpoint cluster region (Mbcr-1) of the BCR gene as found in chronic myelogenous leukaemia (CML), and those within the first intron of this gene. In the former group the molecular events are the same as those found in CML, p210 bcr-abl, encoded by 8.5 kb mRNA; however, a new aberrant protein, p190 bcr-abl, is found in the latter group. Ph translocation is also found in a few cases with malignant lymphoma, but it has not been characterized at the molecular level. We describe here a non-Hodgkin's lymphoma case with primary splenic presentation, which showed a complex Ph translocation. Neoplastic cells were of a B-cell origin (HLA-DR+, sIgM+, sIg lambda +, CALLA-). Molecular studies revealed the expression of p190 bcr-abl with no Mbcr-1 rearrangement. Our case indicates that the same Ph translocation as seen in acute leukaemias can be found in haematologic disorders other than leukaemias, suggesting that a c-abl gene activating mechanism may be involved in the pathogenesis of wide spectrum of haematologic malignancies.

Philadelphia-positive thrombocythemia with a complex translocation involving chromosomes 9, 15, and 22

We report a case of Philadelphia chromosome (Ph) positive thrombocythemia with a complex translocation. G-banding analysis showed the predominant karyotype to be 46,XX,t(9;15;22). Southern blot analysis revealed a rearrangement within the breakpoint cluster region on chromosome 22 similar to findings in chronic myeloid leukemia. These data suggest the presence of a complex Ph translocation involving t(9;15;22)(q34.1 or q34.3;q26.1;q11 or q13).

Cytogenetic and molecular analysis in Philadelphia negative CML

We studied the clinical, hematologic, cytogenetic and molecular biologic features in four patients with Philadelphia (Ph) negative chronic myeloid leukemia (CML). In all four cases the clinical and hematologic characteristics were indistinguishable from Ph positive CML. Cytogenetic analysis showed a normal karyotype in two patients and chromosomal translocations apparently not affecting chromosome 22 in the other two cases. Southern blot analysis using probes of the bcr region, demonstrated a bcr break-point in all four patients. In situ hybridization with bcr, c-abl, and c-sis probes showed unusual hybridization sites for 5′-bcr and c-abl indicating complex chromosomal rearrangements affecting three different chromosomes in the four patients investigated. Using polymerase chain reaction (PCR) followed by hybridization to oligonucleotide probes specific for the bcr-abl fusion region, the expression of a chimeric bcr-abl mRNA was detected. In these patients we demonstrated that (a) CML with a breakpoint in the bcr region without cytogenetically detectable Ph chromosome is characterized by the same genomic recombination of 5′-bcr and c-abl as CML with standard Ph translocation and (b) unusual localization of 5′- bcr and c-abl sequences caused by complex Ph translocation does not interfere with transcription of the bcr-abl fusion gene.

Cytogenetic and Molecular Analysis in Philadelphia Negative CML

AbstractWe studied the clinical, hematologic, cytogenetic and molecular biologic features in four patients with Philadelphia (Ph) negative chronic myeloid leukemia (CML). In all four cases the clinical and hematologic characteristics were indistinguishable from Ph positive CML. Cytogenetic analysis showed a normal karyotype in two patients and chromosomal translocations apparently not affecting chromosome 22 in the other two cases. Southern blot analysis using probes of the bcr region, demonstrated a bcr breakpoint in all four patients. In situ hybridization with bcr, c-abI, and c-sis probes showed unusual hybridization sites for 5’-bcr and c-abl indicating complex chromosomal rearrangements affecting three different chromosomes in the four patients investigated. Using polymerase chain reaction (PCR) followed by hybridization to oligonucleotide probes specific for the bcr-abl fusion region, the expression of a chimeric bcr-abl mRNA was detected. In these patients we demonstrated that (a) CML with a breakpoint in the bcr region without cytogenetically detectable Ph chromosome is characterized by the same genomic recombination of 5’-bcr and c-abl as CML with standard Ph translocation and (b) unusual localization of 5’-bcr and c-abl sequences caused by complex Ph translocation does not interfere with transcription of the bcr-abl fusion gene.

Inversion of chromosome 3 in a case of chronic myelogenous leukemia with abnormal thrombopoiesis

A patient with chronic myelogenous leukemia (CML) associated with a remarkable increase of micromegakaryocytes in bone marrow was revealed to have an abnormality of a long arm of chromosome #3, i.e., inv(3)(q21q26), in addition to a complex Ph translocation: t(9;22;15)(q34;q11;q22). Although several cases of acute leukemia with inv(3)(q21q26) and abnormal megakaryocytes have been reported, this is the first case in which the association of inv(3)(q21q26) with a megakaryocytic abnormality was observed in a patient with CML. Our findings suggest that this structural rearrangement may be more specifically associated with abnormal thrombopoiesis than are other structural anomalies of 3q.