β^s-GLOBIN HAPLOTYPES IN PATIENTS WITH SICKLE CELL DISEASE IN GHANA

We studied β^s-globin haplotypes for the first time in 53 patients with SCD attending the Sickle Cell Clinic at the Korle-Bu Teaching Hospital, Accra, Ghana, and 30 control subjects of healthy blood donors from the year 2009 to 2012. We determined the haplotypes by PCR and RFLP, and the clinical and hematological variables by standard procedures. A total of 9 different haplotypes were defined for the population. These were: Ben/Atp, (Atp:Atypical), Ben/Ben, Ban/Ben, Atp/Atp, Cam/Ben, Ban/Atp, Sen/Sen, Sen/Atp and Cam/Atp. A total of 55 chromosomes (39.8%) were characterized as BEN haplotype, 23 chromosomes (16.7%) as BAN haplotype, 5 chromosomes (3.6%) as CAM haplotype, and 3 chromosomes (2.2%) as SEN haplotype. No Arab Indian haplotype was seen in the population. Fifty-two (52) chromosomes (37.7%) were characterized as Atypical (Atp) haplotype. The Ben and Atp haplotypes were the most prevalent among patients with SCD (51.2%), and HbCC in the control group (27.3%). However, in HbAA subjects, the Ban and Atp haplotypes were most prevalent (p=0.0001). None of the HbSS patients had a Sen haplotype even in the heterozygote. Sen was a rare haplotype in all subjects (p=0.0001) while Cam haplotype was also rare in the SCD population (p=0.0001). The respective allele frequencies for HbS, HbC, and HbA were determined to be 0.53, 0.25 and 0.22. The Linkage Disequilibrium (LD) of an HbS allele on a Ben haplotype was 0.32, while the HbA allele was in linkage with the Ban haplotype (LD=0.21). The hematological indices affirmed that, an HbS allele is necessary for severe disease phenotype.