Hbb-y^tm2.2Fier

1.1 kb of DNA containing the promoter region, exon1, and exon2 was replaced with a floxed PGK-hygro selection cassette in ES cells already containing the targeted allele Hbb-bh1 allele. The selection cassettes in the two genes were subsequently excised by breeding mice to CMV-cre transgenic mice. Because the two loxP sites left behind are in reverse orientation to one another, cre also induced an inversion of the DNA segment between the two sites. This allele is only found in conjunction with Hbb-bh1. (J:145362)