A New δ Chain Variant, Hb A₂-Tunis [δ46(CD5)Gly → Glu; HBD: c.140G>A], Observed in a Tunisian Family in Association with a Compound Heterozygosity for Hb C [β6(A3)Glu → Lys; HBB: c.19G>A] β⁰-Thalassemia [IVS-I-1 (β143, G>A); HBB: c.92+1G>A]

Abstract

We describe a new δ-globin variant, Hb A₂-Tunis [δ46(CD5)Gly → Glu; HBD: c.140G>A]. This hemoglobin (Hb) variant displayed a faster electrophoretic mobility than normal Hb A₂ and was expressed at 3.2%. The molecular defect was characterized by DNA sequencing analysis. Hb A₂-Tunis was found in a carrier of a β⁰-thalassemia (β⁰-thal) [IVS I-1 (β143, G>A); HBB: c.92 + 1G>A] and Hb C [β6(A3)Glu → Lys; HBB: c.19G>A], presenting with a normal Hb A₂ level. Phenotype and genotype investigations revealed that the patient has a total Hb A₂ level of 7.1% that was expected for a β-thalassemia (β-thal) minor carrier.

• β-Thalassemia (β-thal)
• δ-globin
• Hb A₂ variant
• hemoglobinopathy

Acknowledgements

The authors are grateful to all the members of the staff at the Pasteur Institute, Tunis, Tunisia and the Hematology Laboratory of CHU La Rabta, La Rabta, Tunisia, for their close cooperation and important contributions.