Determination of beta-globin gene cluster haplotypes and prevalence of alpha-thalassemia in sickle cell anemia patients in Venezuela.

Sickle cell anemia and alpha-thalassemia have a heterogeneous distribution in Venezuela with a high frequency in the coastal area (sea level) and few cases in the mountains. Most of our population is an ethnic admixture of Europeans (Spaniards colonists), Africans (slaves), and Amerindians. The purpose of our study was to determine the origin of the beta(s) globin haplotype, age and survival dependency, and the admixture among the different African groups in our population. The alpha(3.7) globin gene deletion status was also studied and found in a very high frequency. DNA from peripheral blood of 191 non-related patients (81 with HbS homozygous and 15 patients compound heterozygous for HbS, HbC, HbD with beta-thalassemia, and 95 with sickle cell trait) were studied. The beta(s) chromosome was linked 51% to the Benin Haplotype, 29.5% with the CAR, 12.5% to the Senegal, and 2.5% to the Cameroon. We did not find any significant difference between the haplotype distribution among adults and children and among sickle cell patients and traits. Only 8.6% of the patients have homozygosity for the Benin haplotype. These results show a very high frequency of admixture in our African origin population.