The XmnI Polymorphic Site at 5' to Gγ Gene and its Correlation to the HBF Level and Gγ: Aγ Ratio in β-Thalassemia the Major and the Intermediate Patients from Kermanshah

Introduction: Beta Thalassemia is the most common inherited bloody disorder, affecting synthesis of the beta globin chain of hemoglobin. The type of β-Thalassemia mutation affects on the β-globin chain synthesis that appears as β^° ،β ⁺and^{β++-Thalassemia. The presence of XmnI polymorphic site at the 5}َ region of the ^Gγ-globin gene affects on the rate of ^Gγ chain synthesis and in some conditions influences on the production of HbF. These effects are important in the view of presentation of clinical symptoms in β-Thalassemia patients.

Materials and Methods: In this researches one hundred ninety seven beta Thalassemia the Major and nine beta Thalassemia the Intermediate patients who had been registered in shahid fahmideh hospital in Kermanshah were studied. The XmnI polymorphisms in the region of 5َ to ^Gγ gene was determined by PCR-RFLP procedure. The percent of ^Gγ and ^Aγ chains in HbF were determined by high performance liquid chromatography (HPLC). The HbF levels were determined by electrophoresis (according to patientُs files). Data were subjected to the chi square & analysis of variance (ANOVA).

Results: Analysis of XMNI polymorphism from both groups showed that there were 32(16.3%) XmnI homozygote (+/+) and 44(22.3%) XMNI heterozygote (+/-)in β-Thalassemia the Major group. In patients with β- Thalassemia the Intermediate 5 (55.6%) XmnI homozygote (+/+) and 2 (22.3%) XmnI heterozygote (+/-) were found. The mean level of HbF in β-Thalassemia the Major and the Intermediate patients was 95.3g/dl,85.4g، respectively. Mean ^Gγ / ^Aγ ratio in β-Thalassemia the Major and the Intermediate patients was 2.5% and  2.3% respectively. In the present study  while using ANOVA test we found that ,in beta Thalassemia patients, the presence of XmnI polymorphic site increases HbF levels , ^Gγ percent and ^Gγ / ^Aγ ratio ( p=0.001).

Conclusion: The present study has determined XmnI polymorphic site in β-Thalassemia the Major and the Intermediate patients from Kermanshah and has shown that the presence of this polymorphic site has had a positive influence on HbF production and ^Gγ chain percent.