Factors Associated in Production of Raised Gama Globin Chain in HbE/ ?-Thalassemia ? A Review

Lipika Chaliha, S K Sharma

Abstract: HbE/-thalassaemia genotype represent approximately 50 % of all severe -thalassemia worldwide and is the commonest form of thalassemia in many Asian countries, predominantly prevalent in North-Eastern region exhibiting phenotypes that range from severely symptomatic and transfusion-dependent anaemia in early life to a asymptomatic and clinically -silent- condition that is ascertained by chance in middle age. Assay of m-RNA in cell free system clearly shows a deficiency of m-RNAin heterozygous -thalassemic bone marrow. Compensation for defective - chain synthesis by the - chain locus on the unaffected chromosome in -thalassemia heterozygous have been reported. Some genotypic factors have been reported to affect the synthesis of -chain, such as 3-HS1 (+179 C-T) polymorphism, the (AT) xNy (AT) z motif in the 5-HS2 site, the (AT) x (AT) motif in the -540 region of the -globin gene, GATA-1 (26), and heme-regulated initiation factor 2 alpha kinase (HRI). Also genetic variation at three major loci - XmnI-HBG2, HBS1L-MYB intergenicregion on chromosome 6q23 and variation of rs11886868 (T-C) in the BCL11A geneon chromosome 2p16 has account for relatively large proportion (20-50 %) of the phenotypic variation in HbF levels. HbF levels in HbE/-thalassemia, and other thalassemia syndromes, results from increased erythropoietin levels leading to bone marrow expansion, and possibly increased F-cell production, combined with ineffective erythropoiesis giving a survival advantage to F cells. Among the known genetic factors XmnI, DNA sequence variation (C-T) at position -158 upstream of the G globin gene is one of the gene polymorphism that influence HbF production.

Keywords: Gama Globin, HbF, Xmn-I, HbE, Thalassemia

How to Cite?: Lipika Chaliha, S K Sharma, "Factors Associated in Production of Raised Gama Globin Chain in HbE/ ?-Thalassemia ? A Review", Volume 4 Issue 5, May 2015, International Journal of Science and Research (IJSR), Pages: 261-264, https://www.ijsr.net/getabstract.php?paperid=SUB154121, DOI: https://dx.doi.org/10.21275/SUB154121

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