Unlike gene fusions and mutations in NPM1, which are largely leukaemia-specific and are stable between diagnosis and relapse, mutations in DNMT3A, ASXL1, and TET2 often persist at a high level in patients in long-term mCR, suggesting a reversion to pre-existing non-malignant clonal haematopoiesis of indeterminate potential (CHIP), indicating these mutations are not sufficiently leukaemia-specific to serve as MRD targets. The gene discussed is NPM1; the disease is leukemia.