MDS are a group of clonal hematopoietic stem cell diseases characterized by cytopenia(s), dysplasia in one or more lineages, ineffective hematopoiesis, recurrent genetic abnormalities and increased risk of progression to bone marrow failure or to acute myeloid leukemia (AML) [1,2]. Integration of morphology, cytogenetics, and molecular genetics in the diagnosis and risk stratification of MDS has significantly improved our understanding of the diverse nature of genomic abnormalities in the pathogenesis of MDS and contributed to therapeutic decision-making for MDS. We review here the practice guidelines, including defining features from the 2022 WHO and ICC updates, as well as an emerging molecular prognostic model for diagnosis and risk stratification of MDS.