Molecular spectrum of α-globin gene defects in the Omani population.

We describe the molecular characterization of α-globin gene defects in a cohort of 634 Omani patients. A total of 21 different α gene mutations were found in 484 subjects. Overall, we identified three different large deletions, three small deletions, 11 point mutations [two on the α2 polyadenylation signal (polyA) (HBA2: c.*94A>G), and nine α chain variants], three ααα(anti 3.7) triplication, a 21 nucleotide (nt) duplication on the α1 gene and two novel (presumed) polymorphisms on the α 3.7 kb hybrid gene, namely -5 (C>T) and +46 (C>A). Of these defects, 15 have not been previously reported in the Omani population. This large heterogeneity of α-thalassemia (α-thal) observed in the Omani population could be expected in neighboring Arab countries. The high frequency of α-thal, solely or in association with β-globin gene defects, emphasize the necessity of adding α-thal testing to pre marital programs for accurate genetic counseling.