Influence of Hemoglobin S Haplotypes on the Responses to Hydroxyurea Treatment in Children with Sickle Cell Disease in Abidjan, Côte d’Ivoire

Background: In Côte d’Ivoire so far, the circulating haplotypes have been inferred on the phenotypic profiling of SCD patients. The impact of the circulating haplotypes on the use of Hydroxyurea has not been assessed yet. Therefore the objective of this study is to identify in Abidjan the HbS haplotypes that modulate HU treatment responses. Methods: In a cross-sectional descriptive and analytical study, children aged 5 to 15 years with SCD, and carrying the hemoglobin phenotypes SSFA2 and SFA2, were recruited into a HU treatment cohort. Various parameters on the haplotypes and the outcomes of the treatment were analyzed. Results: Thirty nine children with SCD were included. The phenotypic profile of the cohort was 86.6% of SSFA2 and 15.4% of SFA2. Three haplotypes were found, the Benin haplotype, the Senegal haplotype, and an atypical one. The participants belonged to three genotypes, Benin/atypical (64.1%), Benin/Senegal (33.3%) and Senegal/Senegal (2.6%). Overall, HU treatment was successful in all haplotypes with 12 out of 39 patients failing treatment after 12 months in the Benin haplotype group. The association between HU treatment success and the Benin haplotype was found in terms of the decrease in the number of white blood cells and the students missing class. Conclusion: The study revealed that inferring haplotype based on the phenotypic profile could be inaccurate. The proportion of atypical haplotype that were not previously described in Côte d’Ivoire was high. All the haplotypes seemed to be associated with HU treatment success but some patients with Benin haplotype did not respond well.