Phenotype and genotype-guided backcrossing based mapping and generation of congenic mice. (A) Left: map of murine chromosome 1. The black bracket indicates the boundaries of Rbcstor1, the turquoise box indicates the boundaries of the sixth-generation mouse, and the red box indicates the minimal region containing genetic elements sufficient to confer the poor RBC storage phenotype on a B6 background. Right: pictoral representation of the recombinants obtained in generations 6 to 8 of backcrossing, including the SNPs that define these boundaries (supplemental Table 1). (B) Pedigrees of congenic generations 6 to 8 are shown. (C) Twenty-four–hour recoveries of RBCs stored for 7 days. Left and right panels reflect separate experiments, respectively, each with its own B6, FVB, and F1 controls. These data represent means ± standard deviation (SD) from a representative experiment (n = 3-5 mice per group). These data have been replicated in at least 3 experiments. Statistics calculated using 1-way ANOVA with a Bonferroni post hoc analysis. A significant difference from B6 is indicated by ***P < .0001. (D) Quantitative real-time PCR of each of the gene products contained within the mapped genetic region on chromosome 1. Quantitative real-time PCR was performed on EPs isolated by fluorescence-activated cell sorting from each mouse strain using prevalidated TaqMan assays for each of the 20 genes. Amplification was observed for 10 of the 20 genes. Data shown represent the combined means and SD of expression levels (normalized to expression in B6) from 3 independent experiments. Statistics were calculated by using 2-way ANOVA with a Bonferroni post hoc analysis. A significant difference from B6 is indicated by the following: *P < .05, **P < .005, ***P < .0001.