Heterozygosity of the Complex Corfu δ⁰β⁺ Thalassemic Allele (<i>HBD</i> Deletion and HBB:c.92+5G>A) Revisited

Abstract

The Corfu δ0β+ thalassemic allele is a unique thalassemic allele consisting of the simultaneous presence in cis of a deletion of the δ-globin (Hemoglobin Subunit Delta, HBD) and a single nucleotide variant in the β-globin gene (Hemoglobin Subunit Beta, HBB). The allele has, so far, been described in individuals of Greek origin. The objectives of the study are to ascertain the prevalence of the Corfu δ0β+ allele in comparison to other β-thalassemia variants encountered in Greece using our in-house data repository of 2558 β-thalassemia heterozygotes, and to evaluate the hematological phenotype of Corfu δ0β+ heterozygotes in comparison to heterozygotes with the most common β+- and deletion α0- thalassemia variants in Greece. The results of the study showed a relative incidence of heterozygotes with Corfu δ0β+ at 1.56% of all β-thalassemic alleles, and a distinct hematological phenotype of the heterozygotes characterized by microcytic, hypochromic anemia with normal levels of HbA2 (Hemoglobin A2) and elevated HbF (Hemoglobin F) levels. The application of a specific methodology for the identification of the Corfu δ0β+ allele is important for precise prenatal and antenatal diagnosis programs in Greece.

Keywords

• Corfu δ⁰β⁺ thalassemic allele
• β-thalassemia variants
• β-thal hematological phenotype
• normal HbA2
• high HbF