A stepwise α-thalassemia screening strategy in high-prevalence areas

Salam S. Alkindi, Shoaib Alzadjali, Shahina Daar, Eunice Sindhuvi, Yasser Wali, Anil V. Pathare, Suresh Venugopal, Claudine Lapoumeroulie, Alok Srivastava, Rajagopal Krishnamoorthy

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14 Citations (Scopus)

Abstract

Introduction: Coinheritance of α-thalassemia influences the clinical and hematological phenotypes of β-hemoglobinopathies (β-thalassemia and sickle cell disease) and when present together in significant frequency within a population, a spectrum of clinical forms is observed. Precise molecular characterization of α-thalassemia is important in understanding their disease-modifying role in β-hemoglobinopathies and for diagnostic purposes. Patients and methods: Because currently used approaches are labor/cost-intensive, time-consuming, error-prone in certain genotype combinations and not applicable for large epidemiological screening, we developed a systematic stepwise strategy to overcome these difficulties. We successfully applied this to characterize the α-globin gene status in 150 Omani cord blood samples with Hb Barts and 32 patients with HbH disease. Results: We observed a good correlation between α-globin genotypes and level of Hb Bart's with the Hb Bart's levels significantly higher in both deletional and non-deletional α-globin genotypes. The most common α-globin genotype in HbH cases was αTSaudiα/αTSaudi α (n = 16; 50%) followed by -α3.7/-MED (n = 10; 31%). This approach detects also the α-globin gene triplication as exemplified by the study of a family where the β-globin gene defect failed to explain the β-thalassemia intermedia phenotype. Conclusion: Molecular characterization of α-thalassemia is complex due to high sequence homology between the duplicated α-globin genes and to the existence of a variety of gene rearrangements (small and large deletions of various sizes) and punctual substitutions (non-deletional alleles). The novelty of our strategy resides, not in the individual technical steps per se but in the reasoned sequential order of their use taking into consideration the hematological phenotype as well.

Original languageEnglish
Pages (from-to)164-169
Number of pages6
JournalEuropean Journal of Haematology
Volume91
Issue number2
DOIs
Publication statusPublished - Aug 2013

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Keywords

  • α-thalassemia
  • GeneScan
  • HbH
  • Newborn

ASJC Scopus subject areas

  • Hematology

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