Myeloid Leukemia Factor 1 (Mlf1) is the murine homolog of MLF1, which was identified as a fusion gene with Nucleophosmin (NPM) resulting from the (3;5)(q25.1;q34) translocation associated with acute myeloid leukemia and myelodysplastic syndrome (Yoneda-Kato et al., 1996). Mlf1 was independently isolated using cDNA representational difference to identify genes up-regulated when an erythroleukemic cell line underwent a lineage switch to display a monoblastoid phenotype (Williams et al., 1999). Mlf1 has been shown to enhance myeloid differentiation and suppress erythroid differentiation; however, its mechanism of action is unknown. A yeast two hybrid screen was employed to identify Mlf1-interacting proteins. This screen isolated a number of known protein, as well as several novel molecules, that bound Mlf1. One of these was 14-3-3ξ, a member of a family of molecules that bind phosphoserine motifs and regulate the subcellular localization of partner proteins. Mlf1 contains a classic RSXSXP sequence for 14-3-3 binding and associated with 14-3-3ξ; via this phosphorylated motif (Lim et al., 2002). The aim of this thesis was to characterise a novel Mlf1-interacting protein that had some homology to protein kinases and was named Mlf1 Adaptor Molecule (Madm). Adaptor proteins are molecules that possess no enzymatic or transcriptional activity, but instead mediate protein-protein interactions. Madm is encoded by a gene consisting of 18 exons and promoter analysis suggested Madm expression might be widespread; indeed Northern blotting of adult tissues and in situ hybridization of embryos demonstrated ubiquitous Madm expression. Significantly, the Madm protein sequence is highly conserved across diverse species. / Madm formed dimers and although it contains a kinase-like domain, the protein lacks several critical residues required for catalytic activity, including an ATP-binding site. Purification of recombinant Madm revealed that the protein was not a kinase; however, studies in mammalian cells showed that Madm associated with a kinase and that Madm was phosphorylated on serine residues in vivo and in vitro. Madm also contains a nuclear localization sequence and nuclear export sequence and was shown to localise to both cytoplasm and nucleus by subcellular fractionation and confocal microscopy. The presence of two nuclear receptor binding motifs (consensus MILL) suggests that Madm may have a functional role in the nucleus. Madm co-immunoprecipitated with Mlf1 and co-localized in the cytoplasm. In addition, the Madm-associated kinase phosphorylated Mlf1 on serine residues, including the RSXSXP motif. In contrast to wild-type Mlf1, the oncogenic fusion protein NPM-MLF1 did not bind 14-3-3i; and localized exclusively in the nucleus. Although Madm co-immunoprecipitated with NPM-MLF1 the binding mechanism was altered. As Mlf1 is able to reprogram erythroleukemic cells to display a monoblastoid phenotype and potentiate myeloid maturation (Williams et al., 1999), the effects of Madm on myeloid differentiation was investigated. However, unlike Mlf1, ectopic expression of Madm in M1 myeloid cells suppressed cytokine-induced differentiation. / In summary, the data presented in this thesis reports on the cloning and characterization of a novel adaptor protein that is involved in the phosphorylation of the proto-oncoprotein MIM. Phosphorylation of Mlf1 is likely to affect its interaction with other proteins, such as 14-3-3~. Complex formation, therefore, may well alter the localization of Mlf1 and Madm, and influence hematopoietic differentiation.

京都大学 / 0048 / 新制・課程博士 / 博士(社会健康医学) / 甲第22152号 / 社医博第100号 / 新制||社医||10(附属図書館) / 京都大学大学院医学研究科社会健康医学系専攻 / (主査)教授 川上 浩司, 教授 武藤 学, 教授 髙折 晃史 / 学位規則第4条第1項該当 / Doctor of Public Health / Kyoto University / DFAM

No description available.

Indiana University-Purdue University Indianapolis (IUPUI) / Myelodysplastic syndrome (MDS) is a clonal disease arising from mutated hematopoietic stem cells (HSCs). MDS stem cells originate from pre-leukemic HSCs, which have enhanced competitive advantage over wild-type (WT) HSCs but normal differentiation capacity. Recently, acquired somatic gain-of-function (GOF) TP53 mutations were identified in the blood of aged healthy individuals as well as in patients with MDS. However, the role of GOF TP53 mutations in clonal hematopoiesis and the pathogenesis of MDS is largely unknown. Based upon our previous studies and clinical findings, I hypothesized that GOF mutant p53 drives the development of pre-leukemic HSCs with enhanced competitive advantage, leading to clonal expansion and the pathogenesis of MDS. To test my hypothesis, I examined HSC behaviors in young p53+/+ and p53R248W/+ mice. I discovered that p53R248W enhances the repopulating potential of HSCs without affecting terminal differentiation. I also found that GOF mutant p53 protects HSCs from genotoxic stress and promotes their expansion. To investigate the role of mutant p53 in the pathogenesis of hematological malignancies, I monitored disease development in p53+/+ and p53R248W/+ mice and observed that some mutant p53 mice develop MDS during aging. Therefore, I demonstrated that GOF mutant p53 enhances the repopulating potential of HSCs and drives the development of pre-leukemic HSCs, predisposing aged mutant p53 mice to MDS development. Mechanistically, I found that mutant p53 increases the chromatin accessibility to genes important for HSC maintenance, including pluripotent gene Sox2 and chemokine gene Cxcl9. By performing biochemical experiments, I discovered that GOF mutant p53, but not WT p53, interacts with histone methyltransferase EZH2 and enhances histone H3 lysine 27 trimethylation (H3K27me3) at genes, including Mef/Elf4 and Gadd45g, that negatively regulate HSC self-renewal. Collectively, these findings demonstrated that GOF mutant p53 drives pre-leukemic HSC development through modulating epigenetic pathways. Thus, our studies have uncovered novel mechanistic and functional links between GOF mutant p53 and epigenetic regulators in pre-leukemic HSCs. This research may identify epigenetic regulator EZH2 as a novel target for the prevention and treatment of MDS patients with TP53 mutations.

No description available.

No description available.

Les syndromes myélodysplasiques (SMD) peuvent être conçus comme des conditions pré-leucémiques dans lesquelles l’apoptose avorte les produits de différenciation de cellules souches mutées, potentiellement malignes. Néanmoins, peut-être à cause d’une inhibition progressive de l’apoptose, les SMD se transforment fréquemment en leucémies aiguës myéloïdes (LAM). Nos données indiquent que les SMD à faible risque se caractérisent par l’absence d’activation de NF-κB au sein des cellules portant des altérations cytogénétiques typiques. Par contre, dans les SMD à haut risque de transformation en LAM (ainsi que dans les LAM post-SMD), les cellules souches hématopoïétiques et leurs produits de différenciation montrent une translocation activatrice des sous-unités p50/p65 de NF-κB. L’utilisation d’antagonistes de IKK provoque une inhibition de NF-κB conduisant à une apoptose accélérée, ainsi l’activation de NF-κB serait responsable de la suppression progressive de l’apoptose et donc de la transformation maligne. Ce projet de thèse a consisté à comprendre les mécanismes impliqués dans la dérégulation de l’apoptose dans les SMD/LAM ; ainsi qu’à utiliser des technologies de criblage pour permettre une meilleure compréhension des voies de signalisation impliquées, et à adapter de nouveaux outils d’analyse. Au cours d’une première étude, nous avons montré que les inhibiteurs de méthyltransférase de l’ADN et les inhibiteurs d’histones déacétylases induisent efficacement l’apoptose dans la lignée cellulaire SMD/LAM P39, parallèlement à une inhibition de la translocation de NF-κB du cytoplasme au noyau. Dans une seconde étude, nous avons montré que l’inhibition pharmacologique du récepteur Flt3 induit une inhibition de la voie NF-κB, et pourrait être une cible thérapeutique pertinente. Dans une troisième étude, nous avons montré que l’auto-activation d’ATM chez les patients atteints de SMD/LAM joue un rôle dans l’activation constitutive de NF-κB suggérant qu’ATM serait également une bonne cible thérapeutique dont l’inhibition pourrait réduire le défaut d’apoptose des cellules SMD et LAM. Et enfin, grâce à l’optimisation d’une technique d’analyse d’images à haut débit, nous avons identifié deux composés capables d’induire la mort cellulaire des lignées cellulaires LAM in vitro : le zinc pyrithione et la ouabain. Leurs effets d’inhibition du signal de survie NF-κB, conduisant à une réduction de l’expression de protéines anti-apoptotiques, suggèrent que ces composés pharmaceutiques pourraient être utilisés comme des agents anti-leucémiques. Ce projet de thèse nous a permis de mettre en évidence le potentiel anti-leucémique de différents agents impliqués dans les principales voies de signalisation de l’apoptose dérégulées dans les SMD/LAM, qui pourraient prochainement servir de cibles pour de nouveaux essais thérapeutiques. / Myelodysplastic syndrome (MDS) is a group of hematopoietic stem cell disorders that is characterized by an ineffective hematopoiesis (finaly leading to blood cytopenias) and by a high risk of progression to acute myeloid leukemia (AML). It can therefore be viewed as a preleukemic condition in which apoptosis aborts the differentiation products of potentially malignant mutated (stem) cells. The progression of MDS into AML is associated with progressive inhibition of apoptotsis (by e.g. the expression of antiapoptotic proteins) and a negative prognostic value, suggesting that loss of the apoptotic program could favor the MDS-to-AML transition. Therefore the present project aimed at understanding the mechanisms involved in the deregulation of apoptosis in MDS and AML and the characterization of their underlying signaling pathways by means of standard biochemical and high throughput screening approaches. Our previous work showed that inhibitors of DNA methyltransferases and histone deacetylases effectively induced apoptosis in AML cells in vivo which was associated with an inhibition of NF-κB-dependent transactivation of survival signals. We further found that the pharmacological inhibition of the Flt3 receptor in AML cells decreased NF-κB activation and might therefore constitute a relevant therapeutic target for the treatment of AML. In line with these findings we demonstrated that the constitutive activation of ATM in high-risk MDS and AML patients accounts for the activation of NF-κB suggesting ATM as yet another drugable target for antileukemic therapy. Finally we generated a high throughput image based screening platform, which enabled us to perform large scale drug screening approaches and to identify two compounds with antileukemic properties. Both agent, pyrithione zinc (PZ) and Ouabain (OUA) efficiently induced cell death in AML cells in vitro associated with the inhibition of NF-κB. PZ and OUA exerted significant anticancer effects in vivo, on human AML cells xenografts as well as ex vivo, on CD34+ (but not CD34-) malignant myeloblasts from AML patients. Summarizing this project allowed us to shed some light on the importance of NF-κB during MDS to AML progression and at the same time it helped to identify drugable targets and agents with potential anticancer properties for the treatment of leukemia.

Ce projet de thèse portait sur le développement d’outils microfluidiques pour la toxicologie et la recherche contre le cancer. En permettant l’analyse simultanée d’un très grand nombre de réactions biologiques ou chimiques réalisés dans des compartiments indépendants (ie. gouttelettes), la microfluidique de gouttes offre une sensibilité de détection et une précision sans précédent pour l’analyse de molécules biologiques, telles que l’ADN ou les Anticorps, en comparaison des expériences réalisées conventionnellement en tubes ou en microplaques (essais en « bulk » ou volume). Ce format permet également de réaliser des expériences à très haut débit et est particulièrement pertinent pour la toxicologie, où des analyses robustes de l’effet des médicaments sont nécessaires. De même, ces procédures sont également très adaptées à l’analyse de cellules uniques pour le séquençage ADN ou ARN et l’épigénomique. Tout cela fait de la microfluidique en goutte un outil puissant pour la toxicologie et la recherche sur le cancer. En premier temps, une méthode du comptage précise des cellules encapsulée dans des microgouttelettes, nommée « hémocytométrie microfluidique », a été développée. Un nouvel algorithme de comptage a été proposé. Des cellules bactériennes (Escherichia Coli) et des cellules de 2 lignées humaines différentes (HL60 and H1975) ont été testées. Le nombre de chaque type de cellules a été déterminé avec une haute corrélation entre la théorie (basée sur la distribution de Poisson) et les résultats expérimentaux. Avec ces résultats robustes, un protocole de microfluidique en goutte a été mis en place pour interroger la viabilité cellulaire et la prolifération des 2 lignées humaines. Ces résultats sont en concordance avec ceux de la littérature. Pour la toxicologie, 3 différents modèles, y compris des microsomes (extrait de cellules d’insectes infectées par un baculovirus exprimant le cytochrome P450 3A4 humain, CYP3A4), HepG2-CYP3A4 (modifiée génétiquement pour exprimer le gène CYP3A4 humain), et HepaRG, une lignée hépatique, ont été évaluées pour l’activité enzymatique du CYP3A4, une enzyme largement utilisée en routine pour le criblage de médicament candidat. Les microsomes ont permis de développer un essai fluorogénique permettant de mesurer l’inhibition du CYP3A4. Cependant, ni l’utilisation des microsomes ni des cellules HepG2 exprimant CYP3A4 n’a donné de résultats satisfaisants en microgouttelettes. L’utilisation des cellules HepaRG, une lignée cellulaire qui conserve la majorité de l’expression des cytochromes P450 et des récepteurs nucléaires nécessaire à leur expression, a montré des résultats encourageant à la fois sur les tests de mesure de l’activité enzymatique et d’analyse de l’induction du CYP3A4. Pour la recherche sur le cancer, 4 essais originaux de PCR digitale en gouttes ont été mis en place pour la détection et la quantification de mutations (NRAS, DNMT3A, SF3B1 and JAK2) importante pour les syndromes myélodysplasiques, un groupe hétérogène de maladies touchant les cellules souches hématopoïétiques caractérisées par une hématopoïèse inefficace et des cytopénies périphériques. Finalement, un essai de PCR sur cellule unique encapsulées au sein de billes agarose a été proposé. / This thesis project consists in developing droplet-based microfluidic tools for toxicology and cancer research. Owing to its large numbers of discretized volumes, sensitivity of detection of droplet-based microfluidics for biological molecules such as DNA and antibody is much higher than bulk assays. This high throughput format is particularly suitable for experiments where a robust dose-response curve is needed, as well as for single cell analysis with applications in genomic or sequencing and epigenetics. All above makes droplet-based microfluidics a powerful tool for toxicology and cancer research. In a first part of the work, an accurate cell counting method, named “microfluidics hemocytometry”, has been developed. A new counting algorithm was proposed to count the cells within each droplet. Escherichia Coli and two different human cell lines (HL60 and H1975) were used to validate our strategy. The number of each type of cells in droplets was determined with a high consistency between theory (Poisson distribution) and experimental results. With these robust results, a droplet-based microfluidic protocol has then been established to inquiry both cell viability and proliferation for the two human cell lines. The results are in good agreement with the one of the literature. For the toxicology, 3 different biological models, including microsomes (extracted from baculovirus-infected insect cell expressing human CYP3A4), HepG2-CYP3A4 (genetically modified to express the human CYP3A4 gene) and HepaRG liver cells lines were evaluated for enzymatic activity of cytochromes P450 (CYP3A4), a routinely used enzyme for drug candidate screening. Microsome-based assays were used to validate a fluorogenic inhibition assay. However neither microsome-based assay nor the assay using CYP3A4 expressing HepG2 gave satisfying results in droplet-based format. However, HepaRG cells, a hepatic function-conserved cell line with most cytochrome and related nuclear receptors, demonstrated high relevance both for enzymatic activity testing and CYP3A4 expression induction study. For cancer research, 4 different picoliter droplet-based PCR assays were developed for the detection and quantification of mutations (NRAS, DNMT3A, SF3B1 and JAK2) present in Myelodysplastic syndromes, a heterogeneous group of clonal bone marrow hematopoietic stem cell disorders characterized by ineffective hematopoiesis and peripheral cytopenias. Furthermore, a single cell multistep PCR assay using encapsulation of target DNA in agarose droplets was proposed.

Made available in DSpace on 2016-08-10T10:39:27Z (GMT). No. of bitstreams: 1 CRISTIANO LUIZ RIBEIRO.pdf: 575229 bytes, checksum: 94f5c01fc439ef40126c533a4e1c43c8 (MD5) Previous issue date: 2009-03-16 / This was a study of a low incidenced disease in the population that is myelodysplastic syndrome (MDS). This disease comprises a group of heterogeneous hematopoietic disorders of clonal nature that have in common, varying degrees of bone marrow failure and distinct levels of peripheral blood cytopenias and dysplasia in cell differentiation and may provide various forms of cytogenetic changes, sometimes progressing to leukemia. For MDS, can be identified through the changes with the aid of the karyotype, determine prognosis and to classify them into risk groups, which each patient will be subjected to a more individualized treatment.The objective of this study was to evaluate the cytogenetic and correlated the cytogenetic findings found with the clinical data of patientes in an attempt to improve prognostic information in cases of MDS. This study was conducted at NPR Núcleo de Pesquisas Replicon of Universidade Católica de Goiás e LaGene - de Citogenética Humana e Genética Molecular / SuLeide Superintendência Leide das Neves Ferreira, SES-GO in partnership with the Hospital of the Universidade Federal de Goiás and Hospital Araújo Jorge. We evaluated samples of peripheral blood and bone marrow with the aid of conventional cytogenetics, of 25 patients with clinical indication of MDS, with only 15 confirmed cases with MDS were included in this study. The results of cytogenetic tests showed a wide range of chromosomal abnormalities, including trisomy of chromosomes 21 and 22, monosomy of chromosomes 17 and Y translocation between chromosomes 3q, 8q and 10q, 16q and a duplication on chromosome 1. The deletions appeared more frequently, including deletions on chromosomes 7p, 5q 10q, 11q and 12p. We also observed an isochromosome 17, a ring chromosome and a marker chromosome of unknown origin in addition to the normal karyotypes. This diversity of findings is related to genomic instability, and the monosomy and deletions may be related to inactivation of tumor suppressor genes (TSG) and translocations can activate oncogenes, so these changes are related to the ineffective hematopoiesis in MDS. Also associated with prognosis, the clinical course and progression of the disease, and providing information to assist the diagnosis, classification, monitoring, treatment choice and a more adequate understanding to the broad diversity of the disease. This research will be important to stimulate new research in this area and may establish new partnerships between research centers and treatment, primarily to provide a better quality of life for patients with MDS and their families. / Tratou-se de um estudo sobre uma doença de baixa incidência na população que é a síndrome mielodisplásica (SMD). Esta doença compreende um grupo de desordens hematopoiéticas heterogêneas de natureza clonal que tem em comum, graus variados de insuficiência medular e níveis distintos de citopenias no sangue periférico e displasias na diferenciação celular podendo apresentar várias formas de alterações citogenéticas, evoluindo algumas vezes para leucemia. Para SMD, pode-se através das alterações identificadas com auxílio do cariótipo, determinar o prognóstico e classificá-las em grupos de risco, cujo, cada paciente será submetido a um tratamento mais individualizado. O objetivo deste estudo foi avaliar as alterações citogenéticas nas síndromes mielodisplásicas, utilizando a citogenética convencional, correlacionando os achados citogenéticos encontrados com os dados clínicos dos pacientes, na tentativa de incrementar informações de valor prognóstico para os casos de SMD. O presente estudo foi conduzido no NPR Núcleo de Pesquisa Replicon da Universidade Católica de Goiás e no LaGene Laboratório de Citogenética Humana e Genética Molecular / SuLeide Superintendência Leide das Neves Ferreira, SES-GO em parceria com o Hospital das Clínicas, da Universidade Federal de Goiás e com Hospital Araújo Jorge. Foram avaliadas amostras de sangue periférico e medula óssea com auxílio da citogenética convencional de 25 pacientes com indicação clínica de SMD, sendo que somente os 15 casos confirmados com SMD foram incluídos neste estudo. Os resultados dos testes citogenéticos demonstraram uma grande diversidade de alterações cromossômicas, entre elas trissomias nos cromossomos 21 e 22, monossomias dos cromossomos 17 e Y, translocações entre o os cromossomos 3q;10q e 8q;16q e uma duplicação no cromossomo 1. As deleções apareceram com mais freqüência, entre elas citamos deleções nos cromossomos 7p, 5q 10q, 11q e 12p. Foi observado também um isocromossomo de 17, um cromossomo em anel e um cromossomo marcador de origem indeterminada além dos cariótipos normais. Esta diversidade de achados está relacionada com uma instabilidade gênomica, sendo que as monossomias e as deleções podem estar relacionadas com inativação de genes supressores tumorais (GST) e as translocações podem ativar os oncogenes, logo estas alterações estão relacionadas com a hematopoiese ineficaz em SMD. Também apresenta relação com o prognóstico, o curso clínico e a evolução da doença, oferecendo ainda informações para auxiliar o diagnóstico, a classificação, o acompanhamento, a escolha terapêutica e um entendimento mais adequado em função da grande diversidade biológica da doença. Esta pesquisa será importante para estimular novos estudos nesta área podendo estabelecer novas parcerias entre centros de pesquisas e de tratamento, principalmente para oferecer uma melhor qualidade de vida para os pacientes com SMD e seus familiares.

As síndromes mielodisplásicas (SMD) constituem um grupo heterogêneo de doenças hematológicas de origem clonal, caracterizado por hematopoese ineficaz, citopenia e risco de evolução para leucemia mieloide aguda (LMA). As anormalidades citogenéticas adquiridas são marcadores prognósticos bem estabelecidos em SMD. No entanto, a técnica de citogenética metafásica apresenta limitações, incluindo baixa resolução e necessidade de divisão celular, sendo que defeitos cromossômicos podem não ser detectados. Tecnologias baseadas em microarranjo (array) de DNA, como o Single Nucleotide Polymorphism Array (SNP-A), são importantes para avaliação do genoma normal e neoplásico. O SNP-A foi desenvolvido para o estudo de todo o genoma, apresenta uma resolução superior a citogenética metafásica convencional, pode ser realizado em células na interfase, e detecta alterações cromossômicas não visualizadas pela citogenética metafásica. Além disso, o SNPA fornece dados de genotipagem para detecção de perda neutra de heterozigose, também denominada de dissomia uniparental somática. Regiões cromossômicas com deleção, perda neutra de heterozigose ou ganho são comuns em pacientes com neoplasias hematológicas e sugeriu genes candidatos a supressores de tumor e oncogenes. O objetivo do presente estudo foi a caracterização da coorte de pacientes com suspeita clínica de SMD e o uso integrado do método de citogenética convencional e SNP-A no serviço de hematologia da nossa instituição na investigação de alterações citogenéticas em pacientes com SMD e doenças relacionadas. Durante o período do estudo, foram recebidas um total de 114 amostras de pacientes com suspeita clínica de SMD. A análise clínica, morfológica e citogenética permitiu confirmar o diagnóstico de SMD ou doenças relacionadas em 43 pacientes (SMD [n=34], SMD/NMP [n=5], LMA com alterações mielodisplásicas [n=4]). Vinte e um pacientes foram classificados como citopenia idiopática de significado indeterminado (CISI) e 50 indivíduos apresentaram outros diagnósticos. SNP-A foi realizado em 17 pacientes com SMD e doenças relacionadas. Dentre os pacientes selecionados para o SNP-A, anormalidades cromossômicas foram observadas em 6/17 (35%) casos pelo cariótipo convencional e em 8/17 (47%) casos pela técnica de SNP-A. SNP-A não detectou quatro alterações cromossômicas previamente identificadas pela citogenética convencional: duas translocações balanceadas e duas alterações numéricas. SNP-A confirmou os demais achados identificados pela citogenética convencional e detectou um total de 32 novas lesões (1 ganho, 19 perdas e 12 UPDs) em 6 pacientes com SMD ou doenças relacionadas. SNP-A pode complementar a citogenética convencional na detecção de anormalidades cromossômicas em neoplasias mieloides. / Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematopoietic diseases, characterized by inefficient hematopoiesis, peripheral blood cytopenias and a risk to progress to acute myeloid leukemia (AML). Acquired chromosomal abnormalities have prognostic value in MDS. However, metaphase cytogenetics has some limitations including low resolution and the requirement of cell division, and chromosomal abnormalities may not be detected. New technologies based on array, the Single Nucleotide Polymorphism Array (SNP-A), are able to evaluate the whole genome. The SNP-A has superior resolution compared to metaphase cytogenetics, may be used in interphase cells, and may detect chromosomal abnormalities not detected by metaphase cytogenetics. In addition, the SNP-A read-out includes genotyping calls and hybridization signal strength, corresponding to gene copy number, allowing detecting copy neutral loss of heterozigosity (CN-LOH), also known as uniparental dissomy (UPD). Deletions, copy neutral loss of heterozigosity or gain are frequent in patients with haematopoietic neoplasms and has already suggested the location of tumor suppressor genes and oncogenes. The aim of this study was to characterize the cohort of patients with clinical suspicion of MDS and to establish the integrative use of the conventional cytogenetic and the SNP-A in the investigation of chromosomal abnormalities in patients with MDS and related diseases followed at our institution. The clinical, morphological and cytogenetic evaluation allowed us to confirm the diagnosis of MDS or related disease in 43 patients (MDS [n=34], MDS/MPN [n=5], AML with myelodysplastic changes [n=4]). Twenty-one patients were diagnosed with idiopathic cytopenia with undetermined significance (ICUS) and 50 patients had other diagnosis. SNP-A were performed in 17 patients with MDS and related disease. Chromosomal abnormalities were observed in 6/17 (35%) cases by metaphase cytogenetics, and in 8/17 (47%) of the cases by SNP-A. SNP-A did not detected two balanced translocations and two numerical alterations previously observed by metaphase cytogenetics. SNP-A confirmed all the other findings observed by metaphase cytogenetics and SNP-A detected a total of 32 new lesions (1 gain, 19 losses and 12 UPDs) in 6 MDS and related diseases. SNP-A may complement metaphase cytogenetics to improve the detection of chromosomal abnormalities in myeloid neoplasms.