title: Frequencies and phenotypic consequences of association of α- and β-thalassemia alleles with sickle-cell disease in Bahrain.
abstract: BACKGROUND
  Bahrain has high prevalence rates of sickle cell and thalassemia in the population. This study reports the frequencies and phenotypic characteristics of α- and/or β-thalassemia associated with sickle-cell disease (SCD) in a tertiary care hospital.
  
  
  METHODS
  Adult SCD patients (n = 200) were screened for the common α- and β-thalassemia alleles prevalent in the region using molecular techniques. Results of CBC, hemoglobin analysis, and average annual frequencies of severe pain episodes and numbers of transfused red cell units were documented.
  
  
  RESULTS
  Patients were grouped on the basis of molecular studies as sickle-cell anemia (SS, n = 131), SS/α-thalassemia with three normal genes (n = 27), SS/α-thalassemia with two normal genes (n = 11), sickle-β-thalassemia (Sβ, n = 23), and Sβ with co-inherited α-thalassemia (n = 8). Identified α-thalassemia determinants were -α3.7(n = 52), -α4.2(n = 4), αT-Saudiα (n = 1), and αHphα (n = 1). All β-thalassemia alleles were β0defects. Sickle-thalassemia association resulted in higher hemoglobin, hematocrit, and erythrocyte counts with reduced MCV and reticulocytes. Significant clinical associations were as follows: increased severe pain frequency with α-thalassemia (three-gene group); red cell transfusion with β-thalassemia alleles and female gender.
  
  
  CONCLUSIONS
  One-third of patients with SCD co-inherited α- and/or β-thalassemia alleles and these associations explained some of the observed phenotypic variability. A low prevalence of nondeletion α-thalassemia alleles was observed in these patients. The most significant disease amelioration occurred in SCD associated with two α-thalassemia alleles.
authors.affiliation: Department of Pathology and Al Jawhara Centre for Molecular Medicine and Inherited Disorders, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain.
authors.forename: S
authors.initials: S
authors.lastname: Abuamer
authors.affiliation: Department of Pathology and Al Jawhara Centre for Molecular Medicine and Inherited Disorders, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain.
authors.forename: D K
authors.initials: DK
authors.lastname: Shome
authors.affiliation: Department of Family and Community Medicine, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain.
authors.forename: A
authors.initials: A
authors.lastname: Jaradat
authors.affiliation: Department of Pathology, Salmaniya Medical Complex, Manama, Kingdom of Bahrain.
authors.forename: A
authors.initials: A
authors.lastname: Radhi
authors.affiliation: Department of Pathology, Salmaniya Medical Complex, Manama, Kingdom of Bahrain.
authors.forename: J P
authors.initials: JP
authors.lastname: Bapat
authors.affiliation: Department of Internal Medicine, Salmaniya Medical Complex, Manama, Kingdom of Bahrain.
authors.forename: K A
authors.initials: KA
authors.lastname: Sharif
authors.affiliation: Department of Internal Medicine, Salmaniya Medical Complex, Manama, Kingdom of Bahrain.
authors.forename: J
authors.initials: J
authors.lastname: Al-Touq
authors.affiliation: Department of Internal Medicine, Salmaniya Medical Complex, Manama, Kingdom of Bahrain.
authors.forename: A
authors.initials: A
authors.lastname: Al-Asheeri
authors.affiliation: Department of Internal Medicine, Salmaniya Medical Complex, Manama, Kingdom of Bahrain.
authors.forename: A
authors.initials: A
authors.lastname: Al-Ajami
mesh_terms: D000328:Adult; D000483:Alleles; D000755:Anemia, Sickle Cell / Q000097:blood / Q000453:epidemiology / Q000235:genetics; D001445:Bahrain / Q000453:epidemiology; D005260:Female; D005787:Gene Frequency; D006801:Humans; D008297:Male; D015995:Prevalence; D017085:alpha-Thalassemia / Q000097:blood / Q000453:epidemiology / Q000235:genetics; D017086:beta-Thalassemia / Q000097:blood / Q000453:epidemiology / Q000235:genetics
keywords: Sickle-cell disease; anemia; genotype; phenotype; α-thalassemia; β-thalassemia