Effect alpha globlin gene deletion and gamma globin gene -158 [C/T] polymorphism in beta-thalassemic patients

ABSTRACT

The beta-thalassemias [beta- 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 beta-thalassemia mutations and genotype-to-phenotype correlations were defined in 32 beta- thalassemic patients [beta- 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 Xmnl polymorphism [C/T] in gamma- globin gene position -158 of beta- 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