Calr haploinsufficiency does not affect disease severity in CALRdel52;Calr^+/+ mice. (A) Average complete blood cell counts (n = 21 in each group). Both CALRdel52;Calr^+/+ mice and CALRdel52;Calr^+/− mice developed thrombocytosis, and the degree of the increase was equivalent. (B) Proportions of HSCs and progenitors in BM. Compared with WT mice, increases in HSCs and hematopoietic progenitor cells were observed in both groups of mice, and the degree of the increase was equivalent. (C) Spleen weight of 4- to 6-month-old mice (n = 11-12 in each group). No difference was found in the spleen weight among the 3 groups of mice. (D) Kaplan-Meier plot of WT, CALRdel52;Calr^+/+, and CALRdel52;Calr^+/− mice (n = 21 in each group). All data are presented as means ± SEM. Statistical analyses of survival were performed with the log-rank test. To assess statistical significance among groups, 1-way ANOVA followed by the Tukey–Kramer test was used. *P < .05; **P < .01; n.s., not significant.