Chromosomal aberrations during progression of chronic myeloid leukemia identified by cytogenetic and molecular cytogenetic tools: implication of 1q12-21

Imatinib Mesylate Effectiveness in Chronic Myeloid Leukemia with Additional Cytogenetic Abnormalities at Diagnosis among Black Africans

Imatinib mesylate provides good results in the treatment of CML in general. But what about the results of this treatment in CML associated with additional cytogenetic abnormalities at diagnosis among black Africans? For this, we retrospectively studied 27 cases of CML associated with additional cytogenetic abnormalities, diagnosed in the department of clinical hematology of the University Hospital of Yopougon in Côte d'Ivoire, from May 2005 to October 2011. The age of patients ranged from 13 to 68 years, with a mean age of 38 years and a sex ratio of 2. Patients were severely symptomatic with a high Sokal score of 67%. CML in chronic phase accounted for 67%. The prevalence of additional cytogenetic abnormalities was 29.7%. There were variants of the Philadelphia chromosome (18.5%), trisomy 8 (14.8%), complex cytogenetic abnormalities (18.5%), second Philadelphia chromosome (14.8%), and minor cytogenetic abnormalities (44.4%). Complete hematologic remission was achieved in 59%, with 52% of major cytogenetic remission. The outcome was fatal in 37% of patients. Death was related in 40% to hematologic toxicity and in 30% to acutisation. The median survival was 40 months.

On the Power of Additional and Complex Chromosomal Aberrations in CML

Unregulated proliferation of mainly myeloid bone marrow cells and genetic changes in the hematopoietic stem cell system are important features in Chronic Myeloid Leukemia (CML). In clinical diagnosis of CML, classical banding techniques, fluorescence in situ hybridization (FISH) probing for the Philadelphia chromosome (Ph) or polymerase chain reaction amplifying the fusion products of the BCR-ABL fusion are state of the art techniques. Nevertheless, the genome of CML patients harbors many more cytogenetic changes. These might be hidden in subpopulations due to clonal events or involved in extremely complex aberrations. To identify these additional changes, several cytogenetic and molecular genetic techniques could be applied. Nevertheless, it has been proposed that identifying these aberrations is time consuming and costly and since they cannot be converted into a benefit for the patients, the necessity to perform these investigations has been questioned. In the times where highly specialized medicine is advancing into several areas of cancer, this attitude needs to be reassessed. Therefore, we looked at the usefulness of a combination of different techniques to unravel the genetic changes in CML patients and to identify new chromosomal aberrations, which potentially can be correlated to different stages of the disease and the strength of therapy resistance. We are convinced that the combination of these techniques could be extremely useful in unraveling even the most complex karyotypes and in dissecting different clones contributing to the disease. We propose that by doing so, this would improve CML diagnostic and prognostic findings, especially with regard to CML resistance mechanisms and new therapeutic strategies.

Coexistence of translocation(1,19) and the Philadelphia chromosome in a child's first presentation of chronic myeloid leukemia in blast crisis treated with dasatinib

Chronic myelogenous leukemia (CML) constitutes less than 5% of childhood leukemias. The authors describe a rare case of a 14-year-old boy who presented with CML in blast crisis. Unique to this patient was the evidence of both breakpoint cluster region-c-abl oncogene 1 (BCR-ABL1) fusions as well as an additional unbalanced t(1;19) translocation. This combination has not previously been reported in the same patient. Initial treatment with dasatinib achieved a complete cytogenetic response within 2 months of therapy. This case highlights the heterogeneous presentation of CML in children and rationale for use of dasatinib as a first-line agent for patients with blast crisis.

From dissection of disease pathogenesis to elucidation of mechanisms of targeted therapies: leukemia research in the genomic era

Leukemia is a group of heterozygous diseases of hematopoietic stem/progenitor cells that involves dynamic change in the genome. Dissection of genetic abnormalities critical to leukemia initiation provides insights into the elusive leukemogenesis, identifies distinct subsets of leukemia and predicts prognosis individually, and can also provide rational therapeutic targets for curative approaches. The past three decades have seen tremendous advances in the analysis of genotype-phenotype connection of leukemia, and in the identification of molecular biomarkers for leukemia subtypes. Intriguingly, differentiation therapy, targeted therapy and chemotherapy have turned several subtypes of leukemia from highly fatal to highly curable. The use of all-trans retinoic acid and arsenic trioxide, which trigger degradation of PML-RARalpha, the causative fusion protein generated by t (15;17) translocation in acute promyelocytic leukemia (APL), has led to a dramatic improvement of APL clinical outcome. Imatinib mesylate/ Gleevec/STI571, which inhibits the tyrosine kinase activity of BCR-ABL oncoprotein, has now become the new gold standard for the treatment of chronic myeloid leukemia. Optimal use of chemotherapeutic agents together with a stringent application of prognostic factors for risk-directed therapy in clinical trials has resulted in a steady improvement in the treatment outcome of acute lymphoblastic leukemia. Hence, the pace of progress extrapolates to a prediction of leukemia control in the twenty-first century.

Trisomy 1q in a patient with severe aplastic anemia

Aplastic anemia is a rare, serious disease characterized by hypocellular bone marrow and pancytopenia in the peripheral blood. Most cases are acquired, idiopathic, and without gross cytogenetic abnormalities. A few chromosome abnormalities have recurred among a small subset of patients, most commonly trisomy 8 and monosomy 7. Some of these chromosome abnormalities have prognostic and therapeutic significance, although for most the clinical relevance is not known. We present the case of a 40-year-old man with idiopathic severe aplastic anemia in bone marrow cells with trisomy of the whole long arm of chromosome 1 due to an unbalanced translocation between chromosomes 1 and 15 at breakpoints of q10 and 15q10. This clonal abnormality (which, to our knowledge, has not been previously reported in a patient with aplastic anemia) suggests that genes on 1q may be involved in marrow aplasia.

Human genome research in China

Significant progress in human genome research has been made in China since 1994. This review aims to give a brief and incomplete introduction to the major research institutions and their achievements in human genome sequencing and functional genomics in medicine, with emphasis on the "1% Sequencing Project", the generation of single nucleotide polymorphism and haplotype maps of the human genome, disease gene identification, and the molecular characterization of leukemia and other diseases. Chinese efforts towards the sequencing of pathogenic microbial genomes and of the rice (Oryza sativa ssp. Indica) genome are also described.

Compilation of published comparative genomic hybridization studies

The power of comparative genomic hybridization (CGH) has been clearly proven since the first paper appeared in 1992 as a tool to characterize chromosomal imbalances in neoplasias. This review summarizes the chromosomal imbalances detected by CGH in solid tumors and in hemopathies. In May of 2001, we took a census of 430 articles providing information on 11,984 cases of human solid tumors or hematologic malignancies. Comparative generic hybridization has detected a number of recurrent regions of amplification or deletion that allows for identification of new chromosomal loci (oncogenes, tumor suppressor genes, or other genes) involved in the development, progression, and clonal evolution of tumors. When CGH data from different studies are combined, a pattern of nonrandom genetic aberrations appears. As expected, some of these gains and losses are common to different types of pathologies, while others are more tumor-specific.

Molecular cytogenetic characterization of a novel additional chromosomal aberration in blast crisis of a Ph-positive chronic myeloid leukemia

We describe a novel chromosomal aberration acquired in blast crisis (BC) in a patient affected by Philadelphia-positive chronic myeloid leukemia (CML). Conventional cytogenetic studies at onset showed a classic t(9;22)(q34;q11.2) in all bone marrow cells, confirmed by fluorescence in situ hybridization and reverse transcription-polymerase chain reaction (b3a2) analysis. In BC, the malignant clone developed a new additional cytogenetic abnormality consisting of a deletion of chromosome 21. To our knowledge, this is the first case of del(21) reported in literature associated with BC CML. The use of an appropriate set of BAC/PAC clones restricted the breakpoint to an interval of approximately 100 kb. Sequence analysis did not reveal any known gene in this interval. Oncosuppressor genes distal to the breakpoint could be hypothesized to be involved in the progression of disease toward BC. Identification of new chromosome abnormalities in CML may allow further understanding of specific molecular events leading to disease evolution.

Chronic myelogenous leukemia: laboratory diagnosis and monitoring

Rapid developments have occurred both in laboratory medicine and in therapeutic interventions for the management of patients with chronic myelogenous leukemia (CML). With a wide array of laboratory tests available, selecting the appropriate test for a specific diagnostic or therapeutic setting has become increasingly difficult. In this review, we first discuss, from the point of view of laboratory medicine, the advantages and disadvantages of several commonly used laboratory assays, including cytogenetics, fluorescence in situ hybridization (FISH), and qualitative and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). We then discuss, from the point of view of clinical care, the test(s) of choice for the most common clinical scenarios, including diagnosis and monitoring of the therapeutic response and minimal residual disease in patients treated with different therapies. The purpose of this review is to help clinicians and laboratory physicians select appropriate tests for the diagnosis and monitoring of CML, with the ultimate goal of improving the cost-effective usage of clinical laboratories and improving patient care.

Cytogenetics of chronic myeloid leukaemia

The standard Philadelphia (Ph) translocation t(9;22), its variants and a proportion of Ph-negative cases are positive for the BCR-ABL fusion gene, as determined by molecular analysis. Extensive deletions of chromosome 9 and 22 derived sequences around the translocation breakpoints on the derivative 9 are seen in 10-30% of patients at diagnosis and may confer a worse prognosis. Additional cytogenetic changes can occur in the few months before or during disease progression and are often specific for blast morphology; however, the molecular basis of the most common additional cytogenetic abnormalities is largely unknown. Cytogenetics is important for monitoring patient response to treatment but is increasingly being replaced by the more sensitive and less invasive techniques of RT-PCR and FISH.

Comparative genomic hybridization: uses and limitations

Comparative genomic hybridization (CGH) has contributed significantly to the current knowledge of genomic alterations in hematologic malignancies. Characteristic patterns of genomic imbalances not only have confirmed recent classification schemes in non-Hodgkin's lymphoma, but they provide a basis for the successful identification of genes with previously unrecognized pathogenic roles in the development of different lymphomas. Based on its technical limitations, there is little reason to apply CGH to chromosomes of metaphase cells in routine diagnostic settings. However, the new approach of CGH to DNA microarrays, a procedure termed matrix-CGH, overcomes most of the limitations and opens new approaches for diagnostics and identification of genetically defined leukemia and lymphoma subgroups. Current efforts to develop leukemia specific matrix-CGH DNA chips, which are designed to meet the clinical needs, are presented and discussed.