In myelodysplastic syndromes (MDS), a heterogeneous group of clonal hematopoietic disorders characterized by cytopenia, ineffective hematopoiesis and an increased risk of progression to AML (Haferlach et al., 2014; Shallis et al., 2018), RAD21, STAG2, and SMC1A are the most frequently mutated genes (∼15%) and are associated with poor survival (Cazzola et al., 2013; Kon et al., 2013; Haferlach et al., 2014; Malcovati et al., 2014; Thota et al., 2014). The gene discussed is STAG2; the disease is myelodysplastic syndrome.