Known and New δ-Globin Gene Mutations and Other Factors Influencing Hb A₂ Measurement in the Omani Population

Abstract

Although δ-thalassemia (δ-thal) is not categorized as a severe disease, it is essential to know the molecular spectrum of the δ gene mutations frequently occurring in specific areas, particularly if these areas are characterized by a high rate of β-thalassemia (β-thal) such as Oman. This is because coinherited δ-globin gene defects can interfere with the basic diagnosis of a β-thal carrier when this is based upon the measurement of the Hb A₂ only. Because of that, we have investigated 33 patients with low Hb A₂ levels, collected from different hospitals in Oman. Some cases had a second Hb A₂ fraction, while others had only significantly lower Hb A₂ levels. Among these patients, 20 did carry a δ-globin gene mutation, the rest were carriers of α thalassemia (α-thal) defects or could be iron depleted or both. In total, eight different known mutations and two novel δ variants were found. The characterization of the δ-globin gene mutation spectrum will improve carrier diagnostics and genetic counseling in the Omani population screened for β-thal.

• β-Thalassemia (β-thal)
• δ-globin gene mutation
• Hb A₂
• HBD
• Oman

Acknowledgments

The authors declare to have conducted this study according to local ethical regulations and to have no conflicts of interest in the presented data.