Sickle Cell Disease and Hemoglobin S Prevalence in Botswana

INTRODUCTION: Sickle cell disease is an autosomal recessive blood disorder due to a mutation in the gene encoding the β-globin chain. Epidemiological studies suggest that individuals with the sickle traits have protection against severe and uncomplicated Plasmodium falciparum malaria. In Botswana, the frequency of the HbS allele remains unknown. This study aimed to determine the frequency of the HbS allele in the Ngami and Okavango health districts, areas with relatively high malaria incidence. METHOD: Residual DNA samples previously collected from asymptomatic children during a Malaria Indicator Survey were used for this study, with variant detection conducted via PCR-restriction fragment length polymorphism analysis. RESULTS: A total of 159 samples were analyzed, 79 from Ngami and 80 from Okavango. The results showed that 98.1% of the study subjects had the wild type (Hb-AA) alleles, 1.9% carried sickle cell trait (Hb-AS), and none had homozygous sickle cell (Hb-SS). The frequency of the S allele was found to be 0.0094. CONCLUSIONS: The presence of the S allele in Botswana, albeit at a low frequency, suggests that sickle cell disease can be a potential contributor to chronic hemolytic disorders in Botswana.