In myelodysplastic syndrome, ox-mtDNA contributes to feed-forward bone marrow failure through toll-like receptor 9, an endosomal DNA-sensing pattern recognition receptor known to prime and activate the inflammasome propagating the type 1 IFN–induced inflammatory response in neighboring healthy hematopoietic stem and progenitor cells (Ward et al, 2023). Here, TLR9 is linked to myelodysplastic syndrome.