To validate the suppression of DDR and senescence in cells of LR-MDS patients with RUNX1 mutations and HR-MDS patients compared to that in cells of LR-MDS patients without RUNX1 mutations, we performed two types of analysis: i) immunohistochemical staining of γH2AX on BM FFPE sections and ii) fluorescence detection of senescence-associated β-galactosidase (SA-β-gal) activity in BM sorted cells. The gene discussed is RUNX1; the disease is myelodysplastic syndrome.