Genotype-Phenotype Correlation of Sickle Cell Disease in the United Arab Emirates

We have identified the βs-globin gene haplotypes of 85 patients with sickle cell disease attending the Dubai Thalassemia Center and assessed the influence of haplotype, α-thalassemia, and fetal hemoglobin on the clinical presentation. Identification of the βs haplotypes was based on mutation analyses in the promoter sequences of the Gγ-and Aγ-globin genes. The Arabian-Indian haplotype was found in 52% of the βs chromosomes, whereas the remaining were the Bantu and Benin haplotypes. Those with the Arabian-Indian haplotype in this group had a significantly higher fetal hemoglobin (Hb F) level (mean 27%) and a milder clinical course. In contrast, those with the African haplotypes, Bantu and Benin, expressed relatively lower Hb J levels (mean 11.3%), with a severe clinical presentation. Coinheritance of aL-thalassemia trait in the African haplotypes had an ameliorating effect on hemolytic episodes, but vaso-occlusive crises were more frequent.