A humanized BAC transgenic/knockout mouse model for HbE/beta-thalassemia.

Hemoglobin E (HbE) is caused by a G-->A mutation at codon 26 of the beta-globin gene, which substitutes Glu-->Lys. This mutation gives rise to functional but unstable hemoglobin and activates a cryptic splice site causing mild anemia. HbE reaches a carrier frequency of 60-80% in some Southeast Asian populations. HbE causes serious disease when co-inherited with a beta-thalassemia mutation. In this study, we report the creation and evaluation of humanized transgenic mice containing the beta(E) mutation in the context of the human beta-globin locus. Developmental expression of the human beta(E) locus transgene partially complements the hematological abnormalities in heterozygous knockout mice ((mu)beta(th-3/+)) and rescues the embryonic lethality of homozygous knockout mice ((mu)beta(th-3/th-3)). The phenotype of rescued mice was dependent on the transgene copy number. This mouse model displays hematological abnormalities similar to HbE/beta-thalassemia patients and represent an ideal in vivo model system for pathophysiological studies and evaluation of novel therapies.