Haplotype map of sickle cell anemia in Tunisia.

β-Globin haplotypes are important to establish the ethnic origin and predict the clinical development of sickle cell disease patients (SCD). To determine the chromosomal background of β (S) Tunisian sickle cell patients, in this first study in Tunisia, we have explored four polymorphic regions of β-globin cluster on chromosome 11. It is the 5' region of β-LCR-HS2 site, the intervening sequence II (IVSII) region of two fetal ((G)γ and (A)γ) genes and the 5' region of β-globin gene. The results reveal a high molecular diversity of a microsatellite configuration describing the sequences haplotypes. The linkage disequilibrium analysis showed various haplotype combinations giving 22 "extended haplotypes". These results confirm the utility of the β-globin haplotypes for population studies and contribute to knowledge of the Tunisian gene pool, as well as establishing the role of genetic markers in physiopathology of SCD.