Fetal Hemoglobin in Tunisian Sickle Cell Disease Patient: Relationship with Polymorphic Sequences Cis to the β-Globin Gene.

Fetal hemoglobin (HbF) plays a dominant role in ameliorating morbidity and mortality of hemoglobinopathies. We evaluated the effects of polymorphic markers within the β-globin gene cluster to identify the genetic mechanics that influence HbF on Tunisian sickling patients (n = 242). Haplotype analysis was carried out by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and the framework polymorphism was established by PCR-sequencing, four independent regions of interest were identified: the 5' region of β-LCR-HS2 site, the intervening sequence II (IVSII) region of two fetal (Gγ and Aγ) genes and the 5' region of β-globin gene.

Two new β+ -thalassemia mutation [β -56 (G → C); HBBc. -106 G → C] and [β -83 (G → A); HBBc. -133 G → A] described among the Tunisian population.

Objectives: Different thalassemia mutations have been reported in various ethnic groups and geographical regions in Tunisia. In the present study, we have investigated two rare β(+) -thalassemia mutations, that have not previously been reported in the Tunisian population [β -56 (G > C); HBBc. -106 G > C] and [β -83 (G > A); HBBc.

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.