Restriction mapping of β S locus among tunisian sickle-cell patients

Abstract

Objectives: The polymorphism of the β-globin gene haplotypes and frameworks is useful in the determination of the unicentric and multicentric origin of a mutational event. In our study, the haplotypes linked to the Tunisian β S mutation are determined to improve our knowledge of the chromosomal background of the β-globin gene in sickle-cell anemia in Tunisia. Methods: The authors have investigated 242 unrelated individuals. Haplotype analysis was carried out by polymerase chain reaction-restriction fragment length polymorphism-based methods. Seven polymorphic sites in the β-globin gene cluster were examined. The correlation of these various haplotypes with Hb F expression was studied. Results: The Benin haplotype (Ben) was largely predominant (60.54%) followed by the Atypical haplotype A (8.43%) and Bantu (Ban) (2.71%) haplotypes. A total of 94 chromosomes had atypical haplotypes, 78 (23.49%) had A1 [-----++], 11 (3.31%) had A2 [-------], and five (1.5%) had B1 [--+--++]. The Benin haplotype is associated with a fairly low HbF levels. Conclusion: The very high frequency of the Benin haplotype in our study suggests that the β S mutation present in Tunisia may have originated from the Benin region and was brought to Tunisia along the slave trade routes. However, another atypical haplotype observed a new emergence in our population and could be considered as specific to Tunisian chromosome β S. © 2011 Wiley-Liss, Inc.