RESUMO
The regions of AlQatif and AlAhssa in the Eastern Province of Saudi Arabia are known for their high prevalence of hemoglobinopathies, including ßthalassemia and sickle cell anemia. Previously, the αgene 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 αglobin gene deletion on fetal hemoglobin (HbF) and hemoglobin α2 (HbA2) concentrations in patients with transfusiondependent ßthalassemia. A total of 166 Saudi patients with transfusiondependent ßthalassemia and 337 healthy Saudi patients were included in the study. The α3.7, α4.2, -FIL, -SEA, -MED and -(20.5) gene deletions were identified using multiplex αglobin deletion polymerase chain reaction. The present study revealed that the α3.7 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 3.7α2/α1α2, 3.7α2/α1α12, 3.7α2/3.7α2, 3.7α2HphI/α1α2HphI, 3.7α2/α14.2, 3.7α2/α1polyA1α2, 3.7α12/α1α12, FIL/3.7α2 and 3.7α2/3.7α2Hb Villiers le Bel were also identified in the investigated population. Furthermore, a gradual increase in the concentration of HbF and HbA2 in patients with ßthalassemia and the number of αgene deletions was demonstrated; whereas in healthy patients the level of HbA2 was demonstrated to decrease as the number of αgene deletions increased. Therefore, it can be concluded that the high HbF concentration in the present study is predominantly associated with other mutations associated with ßthalassemia rather than αglobin deletions. Furthermore, the results of the present study also revealed novel αgene deletion genotypes prevalent in the population studied, namely α1α2/α1α2HphI, α1α2HphI/α1α2HphI, α1α2/α1α2Hb Handsworth, 3.7α2HphI/α1α2HphI, 3.7α2/3.7α2Hb Villiers le Bel and -MED/α1α2HphI.
