.1 L1 Sequence May Be Yunnanese (a¦Ã¦Ä¦Â), ¡ã - Thalassemia Deletion Occurred And G¦Ã And-globin Gene Activation Related. Isobutyramide Induced Human And Mouse Globin Gene Expression Studies

Previously we described the Yunnanese (~Aγδβ)~ο·thalassemia deletion that is associated with increased expression of fetal hemoglobin in adults. It reflects failure of the normal mechanisms of hemoglobin switching and reactivation of fetal globin gene in adult. By comparison of phenotypic heterogeneity of fetal genes reactivation and 3' side difference of deletion spanning with other form of (δβ)~ο· (~Aγδβ)~ο· deletions, it has been hypothesized the juxtaposition of enhancer-like elements immediately downstream of it 3'breakpoint. The reported structural analyses suggested that the majority of deletions occurred within the p globin locus was probably related to chromatin configuration, and also showed propensity to the non-homologous events mediated by L1 repetitive elements. Two enhancer-like region identified within 3' juxtaposed DNA in HPFH·1 and HPFH·2 has also been shown containing erythroid DNase I hypersensitive site, suggesting that specific chromatin configuratγion may also be crucial for reacting fetal γ genes. Therefore, the structural analysis of the deletion junction region of Yunnanese (~Aγδβ)~ο·thalassemia is important not only for studying the mechanisms of non-homologous recombination at β-globin locus, but also for studying the reactivation of fetal Gγ-globin gene in this type of deletion.In this study, the 18kb Bglll deletion-junction fragment of Yunnanese (~Aγδβ)~ο· thalassemia and the 11.6kb Bglll fragment of normal DNA region that encompasses its 3' breakpoint were cloned. A set of overlapped fragments that spans the breakpoints and extends further downstream were subcloned from the cloned fragments described above to pGEM·4z vector. By sequencing these plasmids, the deletion-spanning sequence including a noval 1137bp of 3' juxtaposed DNA(GenBank U65397), and a 555bp of normal 3' DNA(GenBank AF034481) across the 3' breakpoint were determined.Comparison of the deletion-spanning sequence with the normal 5'-flanking sequence of Aγ-globin gene (GenBank U01317, HUMHBB), the 5' breakpoint of the deletion was positioned between ·116(A) and -117(G) upstream of the cap site of the...