Approximately 35–45% of patients with deleterious germline RUNX1 variants are expected to develop HMs, most commonly myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), Juvenile Myelomonocytic Leukemia-like, T-cell acute lymphoblastic leukemia (ALL), and occasionally B-cell ALL and other lymphoid malignancies [18–22]. This evidence concerns the gene RUNX1 and myelodysplastic syndrome.