Myelodysplastic syndromes (MDS) are hematological disorders at high risk of progression to secondary acute myeloid leukemia (sAML). However, the mutational dynamics and clonal evolution underlying disease progression are poorly understood at present. In order to elucidate the mutational dynamics of pathways and genes occurring during the evolution to sAML, next-generation sequencing was performed on 84 serially paired samples of MDS patients who developed sAML (discovery cohort) and 14 paired samples from MDS patients who did not progress to sAML during follow-up (control cohort). Results were validated in an independent series of 388 MDS patients (validation cohort). We used an integrative analysis to identify how mutations, alone or in combination, contribute to leukemic transformation. The study showed that MDS progression to sAML is characterized by greater genomic instability and the presence of several types of mutational dynamics, highlighting increasing ( STAG2 ) and newlyacquired ( NRAS and FLT3 ) mutations. Moreover, we observed co-operation between genes involved in the cohesin and Ras pathways in 15-20% of MDS patients who evolved to sAML, as well as a high proportion of newly acquired or increasing mutations in the chromatin-modifier genes in MDS patients receiving a disease-modifying therapy before their progression to sAML.

Patients with low-risk myelodysplastic syndromes (MDS) usually develop iron overload. This leads to a high level of oxidative stress in the bone marrow (BM) and increases haematopoietic cell dysfunction. Our objective was to analyse whether chelation with deferasirox (DFX) alleviates the consequences of oxidative stress and improves BM cell functionality. We analysed 13 iron-overloaded MDS patients' samples before and 4-10 months after treatment with DFX. Using multiparametric flow cytometry analysis, we measured intracellular reactive oxygen species (ROS), DNA oxidation and double strand breaks. Haematopoietic differentiation capacity was analysed by colony-forming unit (CFU) assays. Compared to healthy donors, MDS showed a higher level of intracellular ROS and DNA oxidative damage in BM cells. DNA oxidative damage decreased following DFX treatment. Furthermore, the clonogenic assays carried out before treatment suggest an impaired haematopoietic differentiation. DFX seems to improve this capacity, as illustrated by a decreased cluster/CFU ratio, which reached values similar to controls. We conclude that BM cells from MDS are subject to higher oxidative stress conditions and show an impaired haematopoietic differentiation. These adverse features seem to be partially rectified after DFX treatment.The myelodysplastic syndromes (MDS) comprise a heterogeneous group of malignant haematopoietic stem cell disorders that result in clonal haematopoiesis. This disorder occurs with cytopenia and dysplastic features as a consequence of ineffective haematopoiesis. Clinical presentation and evolution of MDS is heterogeneous. Anaemic syndrome, increased risk of infections and haemorrhagic manifestations are often present. These clinical aspects vary depending on the predominant cytopenia in each case, with anaemia being the most prevalent (up to 80-90% of patients) and the major

Introduction Diagnosis of myelodysplastic syndromes (MDSs) when anemia is the only abnormality can be complicated. The aim of our study was to investigate the primary causes of anemia and/or macrocytosis of uncertain etiology. Methods We conducted a multicenter, prospective study over 4 months in three hematology laboratories. In step 1, we used an automated informatics system to screen 137 453 hemograms for cases of anemia and/or macrocytosis (n = 2702). In step 2, we excluded all patients whose anemia appeared to be due to a known cause. This left 290 patients had anemia of uncertain etiology. In step 3, we conducted further investigations, including a peripheral blood smear, and analysis of iron, vitamin B12, folate, and thyroid hormone levels. Results A differential diagnosis was obtained in 139 patients (48%). The primary causes of anemia were iron deficiency (n = 59) and megaloblastic anemia (n = 39). In total, 25 hematologic disorders were diagnosed, including 14 patients with MDS (56%). The median age of MDS patients was 80 years, 12 had anemia as an isolated cytopenia, and most (n = 10) had lower‐risk disease (IPSS‐R ≤ 3.5). SF3B1 mutations were most frequent (n = 6) and correlated with the presence of ring sideroblasts (100%) and associated with better prognosis (P = 0.001). Conclusions Our prospective, four‐step approach is an efficient and logical strategy to facilitate the diagnosis of MDS on the basis of unexplained anemia and/or macrocytosis, and may allow the early diagnosis of the most serious causes of anemia. Molecular analysis of genes related to MDS could be a promising diagnostic and prognostic approach.