Dnmt3a^R878H/+ confers a fitness advantage selectively in HSCs. (A) Experimental design. (B) Frequency of donor-derived cells in PB of mice transplanted with wild type and Dnmt3a^R878H/+ HSCs, MPP, or MPP^G/M cells (n = 4 to 5 per condition). (C) Frequency of donor-derived cells in BM of primary transplant recipients at 28 weeks. (D) Frequency of donor-derived cells in PB of secondary transplant recipient mice (n = 5 to 8 per condition). (E) Frequency of donor-derived cells in BM of secondary transplant recipient mice. Dots represent individual mice, bars show minimum to maximum. *P < .05, **P < .01, and ***P < .001 by 2-way ANOVA or unpaired t test.