Hemoglobin switching and survival curve analyses of humanized CA mice. (A) Human fetal-to-adult globin gene switching was analyzed in humanized γ^HPFHβ⁰/γβ^A compound heterozygous mice after birth. Human γ-globin and β-globin chain levels in peripheral blood hemolysates were measured by HPLC and plotted as a percentage of total β-like chains across time. High fetal globin chain levels at birth are gradually replaced by adult chains during the first 5 weeks of life. (B) The fractional survival of fully humanized CA (α₂α₁/α₂α_1, γ^HPFHβ⁰/γ^HPFHβ⁰) and littermate control mice are plotted across time. The majority of CA mice die prior to weaning age with a median lifespan of 17 days, whereas all the control littermates survive into adulthood.