EZH2 and myelodysplastic syndrome: Consistently, at the functional level, these ASXL1/EZH2-mutated MDS samples were also sensitive to PARPi treatment (Figure 6C), which induced excessive γH2AX DNA damage foci (Figure 6D) and dsDNA breaks (Figure 6E; supplemental Figure 6E) in the PcG mutant but not in control MLL-rearranged samples.