Polymorphism of the Beta Gene in Homozygous Sickle Cell Patients in Senegal and Its Influence on the Main Complications of the Disease

Sickle cell disease has a great variability of clinical and biological expression that depends on modulatory and environmental genetic factors. This variability in clinical and biological expression encourages us to look for predictors of severity. Hemoglobin F and its genetic determinants are influencing prognostic factors. The objectives of this study were to: determine the prevalence of the Senegal haplotype in homozygous sickle cell patients, study the relationship between this haplotype and the hemoglobin F level and evaluate its influence on the complications of the disease. This is a cross-sectional prospective study that included 100 homozygous sickle cell patients aged over 15 years. A questionnaire was used to collect epidemiological, clinical and biological variables. The hemoglobin F level was measured by capillary method and the analysis of point mutations by restriction fragment length polymorphism (RFLP). These data were collected and analyzed with the software Epi-info 7.2. A value p ≤ 0.05 was considered significant. The Senegal haplotype was found in 90% of patients, of whom 58% were homozygous for this mutation and 32% were heterozygous. The hemoglobin F level averaged 9.5% ± 8.3% and correlated statistically significantly with the allelic frequency. However, only bilary lithiasis correlated with the Senegal haplotype (p <0.005). This study confirms the homogeneity of the Senegal haplotype in the Senegalese sickle cell population and its influence on the synthesis of hemoglobin F. On the other hand, it revealed the existence of a relationship between the Senegal haplotype and bilary lithiasis suggesting the role of this haplotype in the protection against polymerization and hemolysis globally.