Hb F-Wentzville [^Gγ24(B6)Gly→Glu; HBG2: c.74G>A, p.Gly25Glu]: An Unstable ^Gγ-Globin Variant Associated with Neonatal Hemolytic Anemia

Abstract

A novel unstable ^Gγ-globin variant, Hb F-Wentzville [^Gγ24(B6)Gly→Glu; HBG2: c.74G>A, (p.Gly25Glu)], was identified in a young infant who required a single transfusion of erythrocytes for hemolytic anemia. This is the first reported γ-globin variant affecting the highly conserved glycine residue at helical position B6. In the tertiary structure of hemoglobin (Hb), glycine at B6 is in close proximity to another invariant glycine residue at E8. Prior studies have shown that replacement of the B6 or E8 glycine residues with bulkier amino acids disrupts packing between the B and E helices, resulting in Hb instability. Thus, Hb F-Wentzville is analogous to the following unstable β-globin B6 variants: Hb Savannah (HBB: c.74G>T, p.Gly24Val), Hb Riverdale-Bronx (HBB: c.73G>C, p.Gly24Arg), and Hb Moscva (HBB: c.74G>A, p.Gly24Asp).

Keywords:

• Fetal hemoglobin (Hb F)
• hemoglobinopathy
• hemolytic anemia
• tertiary structure
• unstable γ variant

Acknowledgments

We thank the patient and his family.

Disclosure statement

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