Abstract

Background: Xmn-1 polymorphism of (G)globin gene (HBG2) is a prominent quantitative trait loci (QTL) in beta-thalassemia intermediate (beta-TI). In current study, we evaluated the frequency of Xmn-1 polymorphism and its association with beta-globin gene (HBB) alleles and Hb F level in beta-TI patients in Sistan and Balouchestan province, south-east of Iran. Subjects and Methods: 45 beta-TI patients were enrolled. HBB gene mutations and Xmn-1 polymorphism were determined by amplification-refractory mutation system (ARMS) PCR method. Hemoglobin profile was determined using capillary electrophoresis. Results: The study participants consisted of 26 (58) males and 19 (42) females. Mean age of the patients was 10.7+/-3.1 years old. Overall, Xmn-1 polymorphism was observed in 28 (62) patients. Homozygous (TT) and heterozygous (CT) genotypes of the polymorphism represented with frequencies of 12 (26) and 16 (35), respectively. Main recognized HBB gene mutation was IVSI-5(G>C) with homozygous frequency of 44. Non-zero (beta(+)) alleles of HBB gene constituted 11.1 (4 patients with heterozygous beta(+) and one with homozygous beta(+) genotype). Hb F level was significantly higher in patients with at least one Xmn-1allele (67.9+/-Formula: see text17.9%) than those without the polymorphism (19.5+/-20.3%, P<0.0001). Also, patients with homozygous genotype demonstrated significantly higher Hb F compared to heterozygous (CT) cases (respective percentages of 85+/-Formula: see text6.8 and 54.7+/-Formula: see text10.5, p<0.0001). Conclusion: Our results highlighted the role of Xmn-1 polymorphism as the main phenotypic modifier in beta-TI patients in Sistan and Balouchestan province.