Targeted Sequencing identifies patients with pre-clinical MDS at high risk of disease progression
ABSTRACT: The diagnosis of myelodysplastic syndromes (MDS) remains problematic due to the subjective nature of morphological assessment. The reported high frequency of somatic mutations and increased structural variants by array-based cytogenetics have provided potential objective markers of disease however this has been complicated by reports of similar abnormalities in the healthy population. We aimed to identify distinguishing features between those with early MDS and reported healthy individuals by characterising 69 patients who, following a non-diagnostic marrow, developed progressive dysplasia or acute myeloid leukaemia (AML). Targeted sequencing and array based cytogenetics identified a driver mutation and/or structural variant in 91% (63/69) of pre-diagnostic samples with the mutational spectrum mirroring that in the MDS population. When compared with the reported healthy population the mutations detected had significantly greater median variant allele fraction (40% vs 9-10%) and occurred more commonly with additional mutations (≥2 mutations 64% vs. 8%). Furthermore mutational analysis identified a high-risk group of patients with shorter time to disease progression and poorer overall survival. The mutational features in our cohort are distinct from those seen in the healthy population and, even in the absence of definitive disease, can predict outcome. Early detection may allow consideration of intervention in poor risk patients. We performed array based cytogenetics using HumanCytoSNP-12 (Illumina) on 69 patients diagnosed with acute myeloid leukaemia or myelodysplastic syndrome who had a previously non-diagnostic sample. SNP array analysis was performed on all diagnostic samples. In those with a documented abnormality, SNP-A was performed on the corresponding pre-diagnostic sample (n=32).
Project description:We aimed to determine the impact of the common mutations on the transcriptome in myelodysplastic syndromes (MDS). We linked genomic data with gene expression microarray data and we deconvoluted the expression of genes into contributions stemming from each genetic and cytogenetic alteration, providing insights into how driver mutations interfere with the transcriptomic state. We modelled the influence of mutations and expression changes on diagnostic clinical variables as well as survival. Overall design: 159 patients with MDS patients and 17 healthy controls were included in the study. CD34+ cells were isolated from bone marrow samples obtained from MDS patients and healthy controls. Samples were hybridized to Affymetrix GeneChip Human Genome U133 Plus 2.0 arrays
Project description:We assessed lineage involvement by NUP98 translocations in myelodysplastic syndromes (MDS), acute myeloid leukemia (AML), and T-cell acute lymphoblastic leukemia (T-ALL). Single cell analysis by FICTION (Fluorescence Immunophenotype and Interphase Cytogenetics as a Tool for Investigation of Neoplasms) showed that NUP98-translocations with various partners, i.e. NSD1, DDX10, RAP1GDS1, and LNP1, always affected a CD34+/CD133+ hematopoietic precursor. Interestingly, in MDS/AML myelomonocytes, erythroid cells, B- and T- lymphocytes belonged to the abnormal clone, while in T-ALL only CD7+/CD3+ cells were involved. The partner did not appear to play a major role in determining the leukemia phenotype as shown in AML and T-ALL with the same NUP98-RAP1GDS1 fusion. Additional hits, namely mutations of FLT3 and CEBPA in MDS/AML and mutation of NOTCH1 plus MYB duplication in T-ALL, were identified in leukemias with, respectively, myeloid or T-lymphoid phenotype. Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from cryopreserved diagnostic bone marrow or peripheral blood samples. Copy number and Copy neutral LOH analysis of with Affymetrix Cytogenetic 2.7 and Cytoscan HD SNP arrays was performed on 6 NUP98 rearranged leukemias.
Project description:SF3B1, SRSF2 and U2AF1 are the most frequently mutated splicing factor genes in MDS. We have performed a comprehensive analysis to determine the impact of these commonly mutated splicing factors on pre-mRNA splicing in the stem/progenitor cells and in the erythroid and myeloid precursors in splicing factor mutant MDS. Using RNA-seq, we determined the aberrantly spliced genes and dysregulated pathways in bone marrow CD34+ cells of a large group of 82 MDS patients. Splicing factor mutations in MDS result in different mechanistic alterations in splicing and largely affect different genes, but these converged in common dysregulated pathways and cellular processes, including RNA splicing, translation and mitochondrial dysfunction, indicating that these mutations operate through common mechanisms in MDS. Many of these dysregulated pathways and cellular processes can be linked to the known disease pathophysiology and to the phenotypes associated with splicing factor mutations in MDS, whilst several others have not been previously associated with MDS, such as sirtuin signalling. Overall design: RNA-sequencing was performed on bone marrow CD34+ hematopoeitic stem and progenitor cells from patients with myelodysplastic syndrome and healthy controls to identify differential splicing between samples with mutations in the splicing factor SF3B1, SRSF2 or U2AF1 comparative to samples from myelodysplactic syndrome patients without mutations in these splicing factors and healthy controls. Processed data for the CD34+ hematopoeitic stem and progenitor cells are available in the files: CPM_table.txt.gz, Count_table.txt.gz and TPM_table.txt.gz. RNA-sequencing was also performed on monocytic, granulocytic and erythroid precursors from the bone marrow of patients with myelodysplastic syndrome and healthy controls to identify aberrant splicing in samples with mutations in splicing factors SF3B1 and SRSF2 comparative from healthy controls. Processed data for the monocytic, granulocytic and erythroid precursors are available in the files: CPM_table_fractions.txt, Count_table_fractions.txt and TPM_table_fractions.txt.
Project description:Microarray-based classifiers and prognosis models identify subgroups with distinct clinical outcomes and high risk of AML transformation of myelodysplastic syndrome (MDS) An array-based Diagnostic Classifier (DC) model, developed for and evaluated during the MILE study, correctly identified ~50% of the unfractionated MDS specimens submitted to the study; predictions for the other samples were split between “none-of-the-targets” classes and AML signatures, but this distinction also reflected clinical outcome in terms of time to AML transformation. Furthermore, an improved Prognostic Classifier (PC) model was developed that correlated with both time to AML transformation and overall survival. Keywords: Microarray-based gene expression profiling aimed at prediction of AML transformation in MDS Overall design: 164 MDS, 202 AML and 69 non-leukemia bone marrow samples were hybridized to Affymetrix HG-U133 Plus 2.0 GeneChips. This dataset is a subset of the MILE Study (Microarray Innovations In LEukemia) program, headed by the European Leukemia Network (ELN) and sponsored by Roche Molecular Systems, Inc.
Project description:The marrow microenvironment contributes to the pathogenesis of ineffective hematopoiesis in Myelodysplastic Syndromes (MDS). Since mutations and cytogenetic alterations are generally not present in marrow stromal cells, we hypothesized that epigenetic alterations may be responsible for altered stroma functionin MDS. Global DNA methylation of MDS marrow-derived stroma was analyzed by HELP assay and compared to healthy controls. MDS stroma showed aberrant hypermethylation that preferentially occurred outside of CpG islands and involved important signaling pathways.Comparison with stroma derived from 5-Azacytidine (5-Aza) treated MDS patients revealed abrogation of aberrant methylation in treated samples. Integrative expression analysis revealed that the WNT pathway was epigenetically dysregulated in MDS stroma, and the WNT antagonists FRZB and SFRP1 were aberrantly hypermethylated and underexpressed. These epigenetic changes were validated ina co-culture model of stroma and leukemic cells and in an independent set of MDS samples. Importantly, 5-Aza treatment of MDS stroma enhanced hematopoietic activity and erythroid differentiationfrom co-cultured healthy CD34+ cells. These results reveal widespread aberrant epigenetic changes in the MDS marrow microenvironment and demonstrate that DNA methyl transferase inhibitors alter the epigenomic profiles of stromal cells, potentiallycontributing to theirtherapeutic efficacy. The study population consisted of 6 MDS patients and 3 healthy controls. Individual HpaII restriction digest profiles were compared to an internal MspI digest control, to yield differentially methylated fragments for every sample.
Project description:Microarray-based classifiers and prognosis models identify subgroups with distinct clinical outcomes and high risk of AML transformation of myelodysplastic syndrome (MDS); An array-based Diagnostic Classifier (DC) model, developed for and evaluated during the MILE study, correctly identified ~50% of the unfractionated MDS specimens submitted to the study; predictions for the other samples were split between “none-of-the-targets” classes and AML signatures, but this distinction also reflected clinical outcome in terms of time to AML transformation. Furthermore, an improved Prognostic Classifier (PC) model was developed that correlated with both time to AML transformation and overall survival. Experiment Overall Design: 164 MDS, 202 AML and 69 non-leukemia bone marrow samples were hybridized to Affymetrix HG-U133 Plus 2.0 GeneChips. Experiment Overall Design: This dataset is a subset of the MILE Study (Microarray Innovations In LEukemia) program, headed by the European Leukemia Network (ELN) and sponsored by Roche Molecular Systems, Inc.
Project description:Prior studies using DNA microarray platforms have shown alterations of gene expression profiles (GEPs) of marrow cells in myelodysplastic syndromes (MDS). Using the increased sensitivity and accuracy of high-throughput RNA sequencing (RNA-Seq) for detecting and quantifying mRNA transcripts, our study has demonstrated novel significant differences in GEPs between MDS and normal CD34+ marrow cells with 41 genes identified as disease classifiers. Additionally, two main clusters of GEPs distinguished patients based on their major clinical features, particularly between those whose disease remained stable (sMDS) vs patients whose illness transformed to acute myeloid leukemia within 12 months (tMDS). The genes whose expression was associated with disease outcome were involved in functional pathways and biologic processes highly relevant for MDS. Exomic analysis identified MDS-associated pathogenic mutations in virtually all patients tested. MDS subgroups with spliceosome mutations demonstrated distinct differential isoform usage and expression and consequent dysregulation of distinct biological functions. This combination of clinical, transcriptomic and exomic findings provides valuable molecular insights into the mechanisms underlying MDS and its progression to a more aggressive stage and also facilitates prognostic characterization of MDS patients. Overall design: RNA-Seq was performed on CD34+ hematopoietic stem cells derived from healthy individuals and patients with myelodysplastic syndrome.
Project description:A role for reduced ribosomal protein gene dosage in both DBA and 5q- MDS suggests that other forms of MDS might also involve altered expression of ribosomal protein genes. We used microarrays to interrogate the expression of ribosomal proteins from purified hematopoietic stems cells from patients with low risk myelodysplastic syndrome and age-matched healthy controls. Hematopoietic stem cells were sorted from 8 patients with low risk myelodysplastic syndrome and 11 age-matched healthy controls, and total RNA was hybridized to Affymetrix microarrays.
Project description:Myelodysplastic syndromes (MDS) are uncommon entities, heterogeneous clinically and cytogenetically. Recently, a new drug, Lenalidomide, has demonstrated to be very effective in patients with MDS and 5q- reaching 70% of hematological responses whereas patients with MDS without 5q- has only 20-30% of hematological responses. The aim of the present study is to determine genetic alteration in this subset of patients, and describe candidate genes related with response or resistance to Lenalidomide. The aim of the present study is to determine genetic alteration in this subset of patients, and describe candidate genes related with response or resistance to Lenalidomide. Copy number analysis of Affymetrix GenomeWide SNP 6.0 arrays was performed for 2 patients with MDS an isolated 5q- by conventional cytogenetics. There are also 2 samples from separated CD3+ lymphocytes, which were used as references for copy number and LOH inference.
Project description:Myelodysplastic syndromes (MDS) represent a heterogeneous group of neoplastic hematopoietic disorders. Several recurrent chromosomal aberrations have been associated with MDS, but the genes affected have remained largely unknown. To identify relevant genetic lesions involved in the pathogenesis of MDS, we performed SNP-array-based genomic profiling and genomic sequencing in 102 patients. We identified acquired deletions, missense and nonsense mutations in a new gene, TET2, in 26% of MDS patients. Using allele-specific assays, TET2 mutations were shown to be present in the majority of the myeloid cells (56-100%, median 96%). In addition, the mutations were encountered in various lineages of differentiation including CD34+ progenitor cells, suggesting that TET2 mutations occur early during disease evolution. In healthy tissues TET2 expression was shown to be elevated in hematopoietic cells with highest expression in granulocytes, in line with a function in myelopoiesis. We conclude that TET2 is the most frequently mutated gene in MDS known so far. Overall design: Genomic DNA from 102 bone marrow samples and 8 isolated T-cell fractions from MDS patients was hybridized on Affymetrix SNP arrays according to manufacturer's procedures. From one patient, T-cell fraction, mononuclear MDS fraction, and an AML diagnosis sample was hybridized on Affymetrix SNP 6.0 arrays.