During the past ten years, genome-wide analysis of genetic alterations in myelodysplastic syndromes (MDS) has improved our understanding of their pathogenesis. Especially, single nucleotide polymorphism array karyotyping and next-generation sequencing technologies (NGS) have unveiled frequent genetic changes in novel functional pathways, including DNA methylation, RNA splicing and cohesin complex formation, in MDS. Moreover, NGS shed light on the clonal evolution which occurs during the development and progression of MDS, pre-cancerous lesions of MDS, and the effects of germline mutations in MDS.