Fraction of RBCs irreversibly sickled related to measured oxygen tension and donor HbF. (A) ISC percentage of the HbSS blood samples with >1% ISCs at 160 mm Hg samples measured at 3 oxygen tensions. A 1-way analysis of variance was used to identify significant differences, and a Holm-Šídák test was used to compare each oxygen tension. (B) ISC percentage of the 10 HbSS blood samples vs corresponding HbF fraction measured by capillary electrophoresis. Data are fit with a linear regression with the corresponding R² value shown.