Xmn1-158 γGVariant in B-Thalassemia Intermediate Patients in South-East of Iran

Background: Xmn-1 polymorphism of 𝜸(G)globin gene (HBG2) is a prominent quantitative trait loci (QTL) in β-thalassemia intermediate (β-TI). In current study, we evaluated the frequency of Xmn-1 polymorphism and its association with β-globin gene (HBB) alleles and Hb F level in β-TI patients in Sistan and Balouchestan province, south-east of Iran. Subjects and Methods: 45 β-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 (β(+)) alleles of HBB gene constituted 11.1 % (4 patients with heterozygous β(+ )and one with homozygous β(+ )genotype). Hb F level was significantly higher in patients with at least one Xmn-1allele (67.9± [Formula: see text] 17.9%) 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 text] 6.8 and 54.7± [Formula: see text] 10.5, p<0.0001). Conclusion: Our results highlighted the role of Xmn-1 polymorphism as the main phenotypic modifier in β-TI patients in Sistan and Balouchestan province.