Map of 5′HS3 β/γ-globin transgene constructs designed to test LCR dependence on footprints present in the ATR.

Gray boxes indicate the 0.85-kb 5′HS3; white boxes, γ-globin exons; thin lines, γ-globin intron-1 and downstream sequences; and thick lines, β-globin sequences. Within β-globin intron-2, wild-type factor-binding sites are depicted as ovals and A/T tracts as block arrows.