Expression of β-like globin genes in Δ4/wild-type heterozygous mice.

The Hbb^D allele (D) carries the targeted mutation, while the Hbb^S allele (S) is wild type. RNA was analyzed from dpc 10.5 yolk sac, dpc 15.5 fetal liver, and adult peripheral blood by means of RT-PCR assays for Ey, βh1, and adult primers (top, middle, and bottom panels). WT indicates wild-type D/S animals; Δ4 indicates mutant Δ4/S heterozygous mice. S and D mark the RT-PCR products from the S and D alleles, respectively.