Abstract
Thalassemia and sickle cell disease are the most prevalent hemoglobin disorders in the populations of Dammam, Al-Qatif and Al-Ahsa regions in the Eastern Province of Saudi Arabia where our study cases originated. Increased HbF can modify these disorders. Direct sequencing of the HBA2 and HBA1 genes from 157 Saudi subjects revealed a new HBA2 gene conversion in cis or trans in 5.7% of the total. We refer to this new HBA2 gene convert as an alpha 12 (HBAl2) allele due to its combination of alpha l (HBA1) and alpha 2 (HBA2) sequences. Three genotypes, homozygous (-alpha(3.7)(12)/alpha(1)alpha(12)). heterozygous (alpha(1)alpha(2)/alpha(1)alpha(12)) and hemizygous (alpha(1)-(4.2)/alpha(1)alpha(12)) for the alpha 12 allele were observed. The majority of individuals who were positive for the alpha 12 allele had a reduction in the percentage of HbA(2). Further studies are necessary to evaluate the possible effect of these changes on globin gene expression. (C) 2014 Elsevier Inc. All rights reserved.