A new deletion of the β-globin gene cluster has been characterized in two Italian brothers who are heterozygous carriers of a (G)γ(A)γ hereditary persistence of fetal hemoglobin (HPFH). Restriction endonuclease mapping and DNA sequencing of the region encompassing the breakpoint show that the deletion starts 3.2 kilobases (kb) upstream from the δ gene and ends within the enhancer region 3' to the β-globin gene. Here the deletion removes one of the four binding sites for an erythroid specific transcriptional factor (NF-E1). The molecular comparison of the new deletion with others of similar size and location but associated with a δβ-thalassemia phenotype suggests that the residual enhancer element, relocated near γ genes, may increase the fetal hemoglobin (HbF) expression above the level observed in δβ-thalassemia.
|Number of pages||6|
|Publication status||Published - 1990|
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