Three days of treatment with the BCL-2 inhibitor ABT-199 at a dose that did not deplete LT-HSCs isolated from HDs (Extended Data Fig. 9a), either alone or in combination with 5-aza, significantly decreased the number of LT-HSCs isolated from CMP-pattern MDS with BP in co-culture with mesenchymal stromal cells (MSCs; Fig. 3a) by inducing apoptosis (Extended Data Fig. 9b). This evidence concerns the gene BCL2 and myelodysplastic syndrome.