Hemoglobinopathies

Hemoglobin variants and thalassemias, a growing public health problem

PATHOLOGY

Hemoglobinopathies are the most common monogenic disease in Human. Around 7 % of the worldwide population are carriers and 2.7 ‰ births are affected by hemoglobinopathies. These hemoglobin disorders are traditionally endemic among populations originating from Southern Europe, Africa, Middle East and Asia. Due to population migrations, these hemoglobin disorders are occurring today widely across the world.

Hemoglobin variants and thalassemias are two genetically distinct hemoglobin abnormalities. Thalassemias are characterized by a reduced synthesis of the normal globin chain due to gene deletions or mutations. The most common thalassemias are alpha- and beta-thalassemias. The hemoglobin variants are caused by amino acid substitutions in either globin chain. More than 1600 hemoglobin variants have been characterized but only a few are common: Hb S, Hb C, Hb E and Hb D-Punjab.

Hemoglobinopathies can present several clinical symptoms, from benign (mild microcytosis) to the most severe (sickle cell disease, Hb Bart’s hydrops fetalis, …) with multiple organ damage, requiring lifelong transfusions. Diagnosis and follow-up of hemoglobinopathies depend on the presence of abnormal hemoglobin fractions on electrophoresis profiles and the quantification of Hb A2.

Births with a pathological hemoglobin disorder (per 1,000 live births). Source: WHO, 1996