When considering the potential use of BH3 mimetics in MDS, blockade of BCL-2 with either venetoclax or ABT-737 has been demonstrated to result in significant toxicity to primary bone marrow cells from patients with high risk MDS or secondary AML, as demonstrated by reduction in CD34+ cells and decreased colony-forming capacity in vitro, but has no effect on bone marrow cells from patients with low risk MDS or healthy controls (48). Here, CD34 is linked to myelodysplastic syndrome.