Abstract
The regions of Al-Qatif and Al-Ahssa in the Eastern Province of Saudi Arabia are known for their high prevalence of hemoglobinopathies, including -thalassemia and sickle cell anemia. Previously, the -gene deletion has been demonstrated as highly prevalent among populations residing in these two regions. The present study was conducted in order to investigate the implications of the -globin gene deletion on fetal hemoglobin (HbF) and hemoglobin (2) (HbA(2)) concentrations in patients with transfusion-dependent -thalassemia. A total of 166 Saudi patients with transfusion-dependent -thalassemia and 337 healthy Saudi patients were included in the study. The -(3.7), -(4.2), --(FIL), --(SEA), --(MED) and --((20.5)) gene deletions were identified using multiplex -globin deletion polymerase chain reaction. The present study revealed that the -(3.7) gene deletion is the most prevalent (43.5%) in the Saudi populations that were analyzed and is characterized by the deletion of 3,804 base pairs. Numerous genotypes, namely (-3.7)(2)/(12), (-3.7)(2)/(112), (-3.7)(2)/(-3.7)(2), (-3.7)2(HphI)/(HphI)(12), (-3.7)(2)/(-4.2)(1), (-3.7)(2)/(polyA-1)(1)(2), (-3.7)(12)/(112), (--FIL)/(-3.7)(2) and (-3.7)(2)/(-3.7)(Hb Villiers le Bel)(2) were also identified in the investigated population. Furthermore, a gradual increase in the concentration of HbF and HbA(2) in patients with -thalassemia and the number of -gene deletions was demonstrated; whereas in healthy patients the level of HbA(2) was demonstrated to decrease as the number of -gene deletions increased. Therefore, it can be concluded that the high HbF concentration in the present study is predominantly associated with other mutations associated with -thalassemia rather than -globin deletions. Furthermore, the results of the present study also revealed novel -gene deletion genotypes prevalent in the population studied, namely (12)/(HphI)(12), (HphI)(12)/(HphI)(12), (12)/(Hb Handsworth)(12), -(3.7)(HphI)(2)/(HphI)(12), -(3.7)(2)/-(3.7)(Hb Villiers le Bel)(2) and --(MED)/(HphI)(12).