Distribution of Hemoglobin Variants: A Retrospective Study Based on Hemoglobin Electrophoresis Results From a University Hospital in Madagascar

Introduction: Inherited hemoglobin disorders, including sickle cell disease and thalassemias, are a growing public health burden, particularly in low-resource countries. Data from Madagascar remain limited. This study describes the distribution of hemoglobin variants and evaluates methodological considerations using agarose gel electrophoresis in patients referred for laboratory analysis. Methods: A retrospective study was conducted on 553 patients (2014-2019) referred for hemoglobin analysis. Hemoglobin variants were identified using agarose gel electrophoresis (Hydrasys system, Sebia). Demographic data and temporal trends were analyzed. Results: Normal hemoglobin profiles were observed in 133 patients (24.1%). HbAS was the most frequent variant (247; 44.7%), followed by HbSS (105; 19.0%). Isolated alpha-thalassemia and beta-thalassemia were rare, 1 (0.2%) and 7 (1.3%). Combined hemoglobinopathies were observed, predominantly HbAS with alpha-thalassemia (29; 5.2%) and HbAS with beta-thalassemia (17; 3.1%). Agarose gel electrophoresis provided accessible detection of common variants but may underestimate or misclassify rare or complex variants due to co-migration and limited quantification. Conclusion: Sickle cell-related hemoglobinopathies are highly prevalent in Madagascar, with significant genetic heterogeneity including combined forms. While agarose gel electrophoresis is practical in resource-limited settings, complementary techniques such as high-performance liquid chromatography or molecular analysis are recommended for accurate diagnosis. These findings support the need for strengthened screening programs and improved diagnostic capacity to better manage hemoglobinopathies in Madagascar.