Effect Alpha Globlin Gene Deletion And Gamma Globin Gene -158 (C/T) Polymorphism In Beta-Thalassemic Patients

Abstract

The beta-thalassemias (β- thalassemias) are among the most common autosomal recessive disorders. They have a remarkably high frequency in the Mediterranean region and represent one of the most common genetic diseases in Egypt. In this study, the spectrum of β- thalassemia mutations and genotype-to-phenotype correlations were defined in 32 β- thalassemic patients (β- thlassemias major and intermedia) with varying disease severity in two cities of the Suez Canal region. Ten different mutations were identified and the most frequent ones were: IVSI-6 (T-C) (37.5%), IVSI-110 (G-A) (34.4%) and both IVSI-1 (G-A), IVSII-745 (C-G) and -102 (C-G) (12.5% each). There was a wide spectrum of phenotypic severity in all patients. We studied the Xmn1 polymorphism (C/T) in γ- globin gene position -158 of β- thalassemia as a modulating factor of the disease severity. Presence of the polymorphism was found in two patients and this was not sufficient to explain the diversity of the phenotype encountered. Co-inheritance of alpha thalassaemia as a modulating factor was not evident in our patients. In conclusion, we have been unable to find a molecular basis for the benign clinical course in all our patients. Other genetic or acquired factors must be hypothesized which ameliorate the clinical condition.

Keywords: β- thalassemia, Xmn1 polymorphism, α-globin gene deletion.

Egyptian Journal of Biochemistry and Molecular Biology Vol. 26 (2) 2008: pp. 85-100