A Woman with Missing Hb A₂ Due to a Novel (εγ)δβ⁰-Thalassemia and a Novel δ-Globin Variant Hb A₂-Gebenstorf (HBD: c.209G>A)

Abstract

A woman completely lacking Hb A₂ on the high performance liquid chromatography (HPLC) analysis, presented with a novel deletional (εγ)δβ⁰-thal and a δ-globin gene variant. This combination causes a β-thalassemia (β-thal) minor phenotype. The woman was referred by a hematologist due to abnormal blood counts. Multiplex ligation-dependent probe amplification (MLPA) and microarray analysis showed a heterozygous, 177 kb long deletion that removed the locus control region enhancer plus the ε, ^Gγ and ^Aγ genes. Additional sequencing revealed a novel variant HBD: c.209G>A, p.Gly70Asp in the heterozygous state, called Hb A₂-Gebenstorf. The combination of the two variants explains the lack of Hb A₂ in this woman.

Keywords:

• Lack of Hb A₂
• β-thalassemia (β-thal)
• novel locus control region (LCR) enhancer deletion
• novel δ gene variant Hb A₂-Gebenstorf

Acknowledgments

The authors would like to thank all family members for blood donation, personal communication and their written informed consent. Furthermore we would like to acknowledge Dr. Christoph Aegerter, general practitioner, for providing blood samples and his kind cooperation.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.