Elevated Hb A₂ Levels in a Patient with a Compound Heterozygosity for the (β⁺) −31 (A > G) and (β⁰) Codon 17 (A > T) Mutations Together with a Single α-Globin Gene

Abstract

We report the molecular and hematological feature of a Thai woman who had clinical diagnosis of β-thalassemia intermedia (β-TI). Hemoglobin (Hb) high performance liquid chromatography (HPLC) analysis identified Hb A (64.4%), Hb F (12.3%) and Hb A₂/E (15.9%) with small peaks of Hb Bart’s (γ4) and Hb H (β4). She was initially diagnosed as EA Bart’s disease, which occurs from combination of Hb H disease and Hb E (HBB: c.79G > A) trait. However, the Hb analysis using capillary electrophoresis (CE) demonstrated no Hb E, 68.5% Hb A, 15.5% Hb F and 16.0% Hb A₂. DNA analysis showed a compound heterozygosity for (β⁺) −31 (A > G) (HBB: c.-81A > G) and (β⁰) codon 17 (A > T) (HBB: c.52A > T) mutations and deletional Hb H (– –^SEA/–α^3.7). Thus, she was finally diagnosed with a combination of Hb H disease and compound heterozygosity of β⁺/β⁰-thalassemia (β⁺/β⁰-thal). The β-globin mutations could affect not only hematological parameters but also elevate the Hb A₂ levels. These effects could not be ameliorated by the coinheritance of Hb H disease. Therefore, a better understanding of the effects of this combination on hematological analysis data will be useful for providing accurate diagnosis, genetic counseling, prevention and control programs of β-thalassemia major (β-TM).

• β⁺-Thalassemia (β⁺-thal)
• β⁰-thalassemia (β⁰-thal)
• codon 17 (A > T) (HBB: c.52A > T)
• Hb A₂
• −31 (A > G) (HBB: c.-81A > G)

Acknowledgements

The authors thank technicians at the Associated Medical Sciences Clinical Service Center (AMS-CSC), Chiang Mai, Thailand for their assistance.

Declaration of interest

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