Fractional RBC Survival Peripheral blood samples were collected at regular intervals in all participants. Samples were analyzed in real time for percent survival BioRBCs by flow cytometry using a streptavidin-conjugate fluorochrome (streptavidin-phycoerythrin; S-866; Molecular Probes) until the percentage of BioRBCs decreased to the lower limit of detection (approximately <0.06%). Values are represented as the RBC fractional survival given absolute differences in the starting percent biotin fraction among participants. Dots represent individual participant BioRBC fractional survival, shown with a nonlinear regression line and 99% confidence interval bands. (A) Fractional RBC survival curves for participants with HbSS pre- and posttransplant, HbAS, and HbAA. (B) Fractional RBC survival curves for each cohort as compared to the larger group are highlighted in red, including HbSS vs non-HbSS genotypes (HbSC and HbSβ+) in the pre-HSCT cohort, and full DMC vs mixed chimerism in the post-HSCT cohort.