XmnI polymorphism in Egyptian patients with beta-thalassemia major and its correlation with the HbF level

Clinical severity of beta-thalassaemia depends on the types of beta-gene mutations involved. It can also be influenced by genetic factors like concomittant a-thalassaemia and increased gamma-chain production. Several loci are implicated in higher production of HbF. The XmnI restriction site at -158 position of the G gamma-gene is associated with increased expression of the G.-globin gene and higher production of HbF. This study aims to determine the frequency of the G gamma XmnI polymorphism in beta-thalassaemia patients in Egypt and its correlation to the HBF level and clinical severity of the disease. We investigated the XmnI polymorphism in 100 children with beta-thalassaemia major using polymerase chain reaction ( PCR-RFLP)-restriction fragment length polymorphism. We found that ninety-four children had XmnI (-/-) genotype ( 94%) and six children had XmnI (+/-) genotype. On the other hand, the study found that the presence of this polymorphism influences HbF concentration and ameliorate the clinical severity of the disease.