Distinct Transcriptomic and Exomic Abnormalities within Myelodysplastic Syndrome Marrow Cells

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. RNA-Seq was performed on CD34+ hematopoietic stem cells derived from healthy individuals and patients with myelodysplastic syndrome.