RUNX1 and myelodysplastic syndrome: According to BM blast (%) and mutation status of JAK2 and RUNX1, patients with LR-MDS could be further stratified into following three subgroups: low-risk subgroup (BM blast ≤1.5% without JAK2 and RUNX1 mutation), intermediate-risk subgroup (BM blast ≤1.5% with JAK2 or RUNX1 mutation, BM blast >1.5% without JAK2 and RUNX1 mutation), and high-risk subgroup (BM blast >1.5% with JAK2 and/or RUNX1 mutation) (Figure 4A).