All present with lifelong mild-to-moderate thrombocytopenia, but their leukemic risks differ: RUNX1-related thrombocytopenia carries the highest reported lifetime risk [≈25–50%, mainly myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML)], ETV6-related thrombocytopenia is strongly associated with B-cell acute lymphoblastic leukemia (5), and ANKRD26-related thrombocytopenia confers a lower yet significant risk of myeloid transformation (6). The gene discussed is RUNX1; the disease is myelodysplastic syndrome.