Abstract
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.
Highlights
The mutation is unique (GAG GTG) at the 6 codon of the β-globin gene), the clinical and biological expression of sickle cell disease varies considerably depending on the geographical region
Based on analyzes of point mutations resulting in the restriction fragment length polymorphism (RFLP) whose association determines the haplotype, five main foci of sickle cell disease have been described that confirm the multicentric origin of the mutation: the Arabo-Indian haplotype, Benin, Cameroon, Bantu or Central African and Senegal which respectively correspond to specific geographical areas [1]
An EDTA sampling tube was collected from all patients for a blood count and molecular study by PCR / RFLP (Polymerase Chain Reaction / Restriction Fragment Lenght Polymorphism) was done for the detection of point mutations resulting in the polymorphism of a restriction site whose association determines the haplotype
Summary
The mutation is unique (GAG GTG) at the 6 codon of the β-globin gene), the clinical and biological expression of sickle cell disease varies considerably depending on the geographical region. These differences are largely related to environmental factors (climate, social level, pathologies, etc.) and to other genetic factors that have not been fully elucidated. A relationship between haplotype and hemoglobin F (HbF) has been demonstrated. In carriers of the Senegal and Indian haplotype, a higher hemoglobin F level was observed (Lai et al [2] Neonato et al [3]). A relationship between these haplotypes and a lower frequency of the main complications remain controversial Labie et al, [4] Figueiredo et al [5]
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