XmnI POLYMORPHISM AND DISEASE SEVERITY IN PATIENTS WITH BETA THALASSEMIA FROM NORTHERN PAKISTAN.

BACKGROUND Thalassemia is a heterogeneous disorder and several genetic factors influence the severity of thalassemia. An accurate and early diagnosis of a mild thalassemia genotype helps to avoid unnecessary transfusion and its complications. The aim of this study is to identify the association between XmnI polymorphism and disease severity in patients with beta-thalassemia from northern Pakistan. METHODS The cross sectional study was conducted at the Department of Haematology, Armed Forces Institute of Pathology (AFIP) Rawalpindi, from September 2006 to June 2009. A total of 90 subjects including 30 with thalassemia major, 30 with thalassemia intermedia and 30 normal individuals were studied. DNA from each subject was tested for 15 beta-thalassemia mutations and the presence of XmnI polymorphism using Amplification Refractory Mutation System and Restriction Fragment Length Polymorphism respectively. RESULTS One normal and one thalassemia major subject were found to be positive for homozygous and heterozygous XmnI polymorphism respectively. Among the thalassemia intermedia group, XmnI polymorphism was found in 12/30 patients, of whom 10 were homozygous and 2 were heterozygous for it. CONCLUSION XmnI polymorphism is an important genotypic factor in Pakistani population for making a prospective diagnosis of thalassemia intermedia and predicting the severity of the disease.