Quantitative trait locus (QTL) mapping for survival and WBC count in leukemic PR⁺ F₂ mice. QTL and survival curves were generated from analysis of F₂ mice. (A) Survival QTL (Mleu1.1) in the treated model on chromosome 1 at 42.8 cM that is significant at the genomewide level. (B) Survival of ENU-treated F₂ mice is significantly (P < .001) affected by genotype at Mleu1.1. Arrows indicate ENU treatment at 9 and 10 weeks of age. (C) WBC count QTL (Wbc19.1) on chromosome 19 at 47.0 cM that is significant in the covariate model at the chromosome-wide level. (D) At Wbc19.1, SWR/J homozygotes have a higher mean WBC count than B6C3F1 homozygotes (79 ± 128 vs 48 ± 96, respectively, P < .01) independent of treatment status. Data are plotted as median (horizontal bar), 25th to 75th percentile (box) and range (whiskers).