Both α- and β-thalassemia (α- and β-thal) are highly prevalent in the population of the Al-Qatif and Al-Ahsa regions in the Eastern Province of Saudi Arabia. This study provides a more precise picture of the α-thal mutations prevalent in 104 transfusion-dependent β-thal patients in the Eastern Province. Detection of α-thal mutations was carried out using the α-globin StripAssay kit. A total of 12 α-thal mutations (21 genotypes) were identified in 33.7% of the chromosomes (46 patients). The heterozygous and homozygous -α(3.7) (α(+)) deletion mutations were the most prevalent in the β-thal patients (21.7%). We identified three α(0) deletions [- -(MED), - -(FIL) and -(α)20.5] that have not been previously reported for the population of Saudi Arabia. The seven point mutations identified in the β-thal patients were: codon 14 [TGG>TAG (α1)], codon 59 [GGC>GAC (α1)] (Hb Adana), polyadenylation signal site (polyA1) [AATAAA>AATAAG (α2)], codon 142 [TAA>TCA (α2)] (Hb Koya Dora), codon 59 [GGC>GAC (α2)] (Hb Adana), initiation codon [ATG>ACG (α2)] and the ααα(anti 3.7) gene triplication. The Hb Koya Dora mutation occurred at the highest frequency (15.38%). Comparison of the clinical phenotype of β-thal patients, with and without an α-thal mutation, showed that patients with β-thal alone had a significantly elevated level of alanine transaminase (ALT) (mean 72.5 IU/L) and aspartate transaminase (AST) (mean 71.8 IU/L) (p <0.005). In addition, the β-thal patients without an α-thal mutation had a higher percentage of osteoporosis (16.6%), fractures (12.5%), and splenectomies (58.3%). This confirms previous data that the co-inheritance of α-thal in β-thal patients results in the amelioration of the clinical phenotype of β-thal patients. Moreover, the high frequency of α- and β-thal in the Eastern Province of Saudi Arabia and their coinheritance, necessitates the inclusion of α-thal testing in the current pre marital testing program to highlight the risk to the offspring of affected individuals.
The regions of Al‑Qatif and Al‑Ahssa in the Eastern Province of Saudi Arabia are known for their high prevalence of hemoglobinopathies, including β‑thalassemia and sickle cell anemia. Previously, the α‑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 α‑globin gene deletion on fetal hemoglobin (HbF) and hemoglobin α2 (HbA2) concentrations in patients with transfusion‑dependent β‑thalassemia. A total of 166 Saudi patients with transfusion‑dependent β‑thalassemia 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 α‑globin 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/α1‑4.2, ‑3.7α2/α1polyA‑1α2, ‑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 β‑thalassemia and the number of α‑gene deletions was demonstrated; whereas in healthy patients the level of HbA2 was demonstrated to decrease as the number of α‑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 β‑thalassemia rather than α‑globin deletions. Furthermore, the results of the present study also revealed novel α‑gene 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.
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