Genomic DNA and hemoglobin analysis of mice derived from targeted ES cell lines 1 and 2. (A) After removal of the PGK/Hygro marker from corrected ES cell clone 1 (–1400 γ-β^A/–1400 γ-β^S) and clone 2 (–383 γ-β^A/–1400 γ-β^S), cells were injected into C57BL/6 blastocysts. Chimeric males obtained from these blastocysts were mated with hα/hα, –1400 γ-β^S/mβ females and offspring were screened for the corrected genotypes (–1400 γ-β^A/–1400 γ-β^S and –383 γ-β^A/–1400 γ-β^S) by PCR of tail DNA and Bsu36I digestion. (B) IEF gel of hemolysates from mice identified as sickle and corrected animals in panel A. The last 3 lanes are human control hemolysates from a sickle patient, an individual with sickle trait, and an unaffected individual. Of interest, the ratio of HbA to HbS in corrected animals mimics the ratio in humans with sickle trait.