title: A novel HBA2 gene conversion in cis or trans: "α12 allele" in a Saudi population.
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 α12 (HBA12) allele due to its combination of α1 (HBA1) and α2 (HBA2) sequences. Three genotypes, homozygous (-α12(3.7)/α1α12), heterozygous (α1α2/α1α12) and hemizygous (α1- (4.2)/α1α12) for the α12 allele were observed. The majority of individuals who were positive for the α12 allele had a reduction in the percentage of HbA2. Further studies are necessary to evaluate the possible effect of these changes on globin gene expression.
authors: Prince Mohammed Centre for Research and Consultation Studies, University of Dammam, P.O. Box 1982, Dammam 31441, Saudi Arabia. Electronic address: fbalexander@ud.edu.sa.
authors: J Francis
authors: JF
authors: Borgio
authors: Prince Mohammed Centre for Research and Consultation Studies, University of Dammam, P.O. Box 1982, Dammam 31441, Saudi Arabia.
authors: S
authors: S
authors: AbdulAzeez
authors: Department of Pathology, King Fahd Hospital of the University, Al-Khobar, Saudi Arabia.
authors: Awatif N
authors: AN
authors: Al-Nafie
authors: Dammam Maternity and Child Hospital, Dammam, Saudi Arabia.
authors: Zaki A
authors: ZA
authors: Naserullah
authors: Dammam Maternity and Child Hospital, Dammam, Saudi Arabia.
authors: Sana
authors: S
authors: Al-Jarrash
authors: Department of Pediatrics, King Fahd Hospital of the University, Al Khobar, Saudi Arabia.
authors: Mohammed S
authors: MS
authors: Al-Madan
authors: Department of Internal Medicine, King Fahd Hospital of the University, Al-Khobar, Saudi Arabia.
authors: Fahad
authors: F
authors: Al-Muhanna
authors: Center of Excellence in Sickle Cell Disease, Department of Medicine, Boston University School of Medicine, Boston, MA, USA.
authors: Martin H
authors: MH
authors: Steinberg
authors: Prince Mohammed Centre for Research and Consultation Studies, University of Dammam, P.O. Box 1982, Dammam 31441, Saudi Arabia.
authors: Amein K
authors: AK
authors: Al-Ali
mesh_terms: D000328:Adult; D000483:Alleles; D000755:Anemia, Sickle Cell / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology; D001483:Base Sequence; D002648:Child; D005260:Female; D015870:Gene Expression; D005838:Genotype; D057898:Hemizygote; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D020033:Protein Isoforms / Q000235:genetics; D012529:Saudi Arabia / Q000453:epidemiology; D055542:alpha-Globins / Q000235:genetics*; D017085:alpha-Thalassemia / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology; D055544:beta-Globins / Q000235:genetics*; D017086:beta-Thalassemia / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology
chemical_list: D020033:Protein Isoforms; D055542:alpha-Globins; D055544:beta-Globins
keywords: Gene conversion; HbA(2); Thalassemia; α-Globin gene; α12 allele