Contribution of Xmn I Polymorphism in the Variation of Hemoglobin F in Thalassemia Intermedia Patients in Pakistan

Background: The −158 (C→T) nucleotide change, known as Xmn I polymorphism, occurs in G γ-globin gene promoter and may result in elevated fetal hemoglobin (HbF). However some studies did not find any association of HbF with the mutation. This study was taken to confirm the influence of Xmn-I polymorphism on HbF production in thalassemia intermedia patients in Pakistani population. Methods: Blood samples from 100 known thalassemia intermedia patients were collected and analyzed for Xmn -I polymorphism and levels of hemoglobin F. Results: High levels of HbF were found in Thalassemia intermedia patients being heterozygous and homozygous for Xmn -I polymorphism. Conclusion: Xmn I polymorphism (C-T) of the G γ-globin gene promoter is associated with increased expression of the G γ-globin gene, higher production of HbF and lesser clinical severity.