IntroductIon Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal diseases of pluripotent hematopoietic stem or progenitor cells. They are characterized by ineffective hematopoiesis, increased apoptosis, peripheral blood cytopenias, and propensity to evolve into acute myelogenous leukemia (AML). 1-3 Clonal chromosome aberrations can be detected in 30-60% of primary MDS and 80% of secondary MDS cases. They are most often unbalanced aberrations; losses or gains of the whole chromosomes or their fragments that cause mainly losses of caretaking and gatekeeping genes, or gains of oncogenes or genes related to multidrug resistance. 4-8 The most common aberrations in MDS are: deletion of the long arm of chromosome 5 (del5q = 5q-), monosomy of chromosome 7 (-7), deletion of the long arm of chromosome 7 (del7q = 7q-), trisomy 8 (+8), deletion of the short arm of chromosome 17 (del17p = 17p-) with TP53 gene locus, deletion of the long arm of chromosome 20 (del20q = 20q-). 9 Detection of chromosome aberrations is useful in differential diagnosis of MDS, myeloproliferative diseases, aplastic anemia or paroxysmal nocturnal hemo globinuria. It is also useful

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We investigated bone marrow cells of 70 acute lymphoblastic leukemia children by conventional cytogenetics (CC), fluorescence in situ hybridization (FISH), and reverse transcription polymerase chain reaction (RT-PCR) methods. CC and RT-PCR for fusion genes BCR/ABL, MLL/AF4, E2A/PBX1, TEL/AML1 were performed at diagnosis in each patient. FISH was performed to verify the presence of fusion genes and MLL rearrangements and to estimate the percentage of abnormal cells. Karyotypes were obtained in 59 (84%) of 70 cases. Thirty-five (59%) of 59 cases revealed chromosome aberrations. Hyperdiploidy>50 chromosomes was present in nine cases, hyperdiploidy 47-50 chromosomes in six, pseudodiploidy in 15, and hypodiploidy in five. BCR/ABL was present in two cases, PBX1/E2A in two, and TEL/AML1 in 14. MLL/AF4 was not found, but the rearrangements of MLL gene were present in five children. The addition of RT-PCR and FISH to CC was of the utmost importance. One of two Ph translocations and one of two t(1;19) were first revealed by RT-PCR. Moreover, FISH showed the percentage of TEL/AML1(+) cells that turned to be an important prognostic factor. The outcome was the best for the children with hyperdiploidy>50 chromosomes without structural changes. It was also good for those with TEL/AML1 present in >or=80% of cells without chromosome aberrations. The presence of pseudodiploidy correlated with poor outcome. The outcome for patients with t(9;22)-BCR/ABL or 11q23-MLL rearrangement was the worst in study group. The presence of BCR/ABL caused eight times increase of risk of death; MLL rearrangements caused 12 times increase.

T-cell acute lymphoblastic leukemia (T-ALL) is a highly heterogeneous disease, and numerous genetic aberrations in the leukemic genome are responsible for the biological and clinical differences among particular ALL subtypes. However, there is limited knowledge regarding the association of whole-genome copy number abnormalities (CNAs) in childhood TALL with the course of leukemia and its outcome. The aim of this study was to identify the pattern of whole-genome CNAs in 86 newly diagnosed childhood TALL cases using a high-density single-nucleotide polymorphism array. We analyzed the presence of whole-genome CNAs with respect to immunophenotype, clinical features, and treatment outcomes. A total of 769 CNAs, including trisomies, duplications, deletions, and segmental loss of heterozygosity, were detected in 86 analyzed samples. Gain or loss of chromosomal regions exceeding 10 Mb occurred in 46 cases (53%), including six cases (7%) with complex chromosomal alterations. We observed that microdeletions in selected genes (e.g., FIP1L1 and PDGFRB) were related to the clinical features. Interestingly, 13% of samples have a duplication of the two loci (MYB and AIH1-6q23.3), which never occurred alone. Single-nucleotide polymorphism array significantly improved the molecular characterization of pediatric TALL. Further studies with larger cohorts of patients may contribute to the selection of prognostic CNAs in this group of patients.