The human β-globin gene contains a downstream developmental specific enhancer

textabstractThe human P-globin gene is part of a multigene family and is expressed specifically in adult human erythroid tissue (for review, 1). When the human P-globin is introduced into fertilized mouse eggs, it is first activated in foetal liver and remains expressed in adult erythroid tissues (2,3,4). It therefore mimicks the pattern of expression of its murine counterpart. It has previously been shown in tissue culture (5) and transgenic mice (4) that sequences downstream from the 0-globin promoter are involved in this regulation. We now show that at least part of these sequences are located 0.5-1.2kb downstream from the polyA addition site and constitute a transcriptional enhancer element that is erythroid and developmental specific.