Frequency of G-Globin Promoter -158(C>T) Xmnl polymorphism and its correlation with Beta thalassaemia mutations in Bangladeshi population

Background: In Bangladesh, more than 14000 children on are born annually with in thalassaemia – a common congenital disease Hb E trait is 6.1%. Hb E beta thalassaemia is the most common type of thalassaemia, followed by Beta thalassaemia major. Objectives: To determine the frequency of Xmn1 polymorphism and its association with Beta thalassaemia mutations. Methods: A total of one hundred and four Bangladeshi thalassaemia patients were analysed. Amplification Refractory Mutation System (ARMS) was utilized for Beta thalassaemia mutations and digestion of the PCR product using Xmn1 restriction enzyme Pdml for Xmn1 polymorphism. Results: Xmn1 polymorphism was detected in seventy patients of which 60(57.69%) were heterozygous for Xmn1 polymorphism and seventeen (16.35%) were homozygous. The most common genotype found was heterozygous Xmn1(-/+)seen in 57.70%. The age of presentation of thalassaemic patients was delayed in those who had Xm1 polymorphism.The mean age of presentation of Hb E beta thalassaemia was 13.35 years having homozygous Xm1 polymorphism,7.21 years in heterozygous and 6.25 years without Xmn 1 polymorphism. The most common mutation detected was Cd26 (G-A) +IVS 1-5(G-C) in fifty eight patients in which thirty nine (67.24%) were heterozygous for Xmn 1 polymorphism and 8 (13.79%) were homozygous (+/+).The second most common mutation observed was Cd26(G-A)+30(G-C) seen in fourteen patients where 57.14% were homozygous for Xmn 1 polymorphism and 35.71% were heterozygous. In thalassaemia major 9 (90%) were negative for Xmn1 polymorphism. Allele frequency of Xmn 1 polymorphism was 0.45. Conclusion: The association of Xmn1 polymorphism with two common mutations seen in Hb E beta thalassemia patients may be utilized for hydroxyurea therapy to reduce the requirement of blood transfusion. Bangladesh Med Res Counc Bull 2021; 47(2): 219-224