Topic overview

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Structural hemoglobin variants result from changes to a globin chain’s amino-acid sequence, whereas thalassemias involve reduced synthesis of one or more globin chains. The snapshot describes inheritance as almost always autosomal recessive, with heterozygotes typically asymptomatic carriers. It highlights characteristic findings linked to selected variants, including HbS polymerization when deoxygenated and the elevated HbA₂ associated with β-thalassemia minor. α-thalassemia is organized by the number and arrangement of affected genes, from trait to HbH disease and fetal Hb Barts. Electrophoresis or HPLC can reveal characteristic migration patterns, while DNA analysis can identify mutations or deletions. These patterns provide a framework for understanding classification, clinical features, and diagnosis.