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" The effects of variation in the HS-2 and G(gamma) 5' flanking sequence of the beta(S) chromosome on the expression of fetal hemoglobin "
J. J. Thomas
K. Lanclos
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Latin Dissertation
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English
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| Record Number
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1113458
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TLpq304473747
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| Main Entry
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J. J. Thomas
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K. Lanclos
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| Title & Author
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The effects of variation in the HS-2 and G(gamma) 5' flanking sequence of the beta(S) chromosome on the expression of fetal hemoglobin\ J. J. ThomasK. Lanclos
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| College
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Medical College of Georgia
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| Date
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1998
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1998
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| Degree
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Ph.D.
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| Page No
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123
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| Abstract
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usd\rm\beta\sp{S}usd-chromosome haplotypes are peculiar to specific regions of Africa and Asia, and, are associated with different levels of fetal hemoglobin in sickle cell patients. Among these haplotypes, usd\rm\beta\sp{S}usd-chromosomes found in the Senegal and the Saudi-Indian regions are associated with relatively high levels of HbF expression, whereas those around the Benin, Bantu and the Cameroon regions show low levels of HbF expression. The roles of 5HS-2 and the 5 flanking (promoter region) region in the expression of globin genes are well documented. The haplotype specific variations found in these regions have been postulated to be involved in the regulation of HbF expression. In this study, we have analyzed the effect of sequence variations in regulatory regions of the Senegal, Benin and Bantu 5 HS2 and 5 flanking region of the usd\rm\sp{G}\gammausd gene on CAT expression. Furthermore, we studied the effects of hydroxyurea, 5-azacytidine and butyrate with these sequences on the reporter gene activity. A higher level of reporter gene activity was observed when the LCR HS-2 fragment originated from the Senegal haplotype in combination with the Benin usd\rm\sp{G}\gammausd 5 flanking region (Sen/Ben), when compared to the Sen/Sen, Ben/Ben or the Ben/Sen combinations, in K562 cells. Conversely, reporter gene activity was always low when the plasmids contained LCR HS-2 from the Benin usd\rm\beta\sp{S}usd haplotype. A diminution was observed in K562 cells when the promoter originated from the Bantu usd\rm\beta\sp{S}usd chromosome. The lower expression was independent of the origin of the 5HS-2 sequence: combinations of the Bantu promoter were measured with the Benin, Bantu or Senegal 5HS2 sequences in K562 cells. However, expression of the same plasmids in MEL cells showed no difference in CAT expression among the various sequence combinations studied. Either a lack or a decrease in the reporter gene activity was observed in response to hydroxyurea treatment. Preliminary studies done with 5-azacytidine failed to show any effect. Interestingly, on treatment with butyrate a significant increase in the expression of the reporter gene was observed when the plasmids contained either the Benin HS-2 or the Bantu usd\rm\sp{G}\gammausd 5 flanking region.
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beta
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Biological sciences
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G
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gamma
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sb
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sp{
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