Abstract
We report the molecular and hematological identifications of a Hb A2 variant [coinheritance of Hb A2-Melbourne (HBD: c.130G>A) and Hb E (HBB: c.79G>A)] found for the first time in the Lao People’s Democratic Republic (PDR). The subject was a 29-year-old pregnant Laotian woman who was a foreign worker in Thailand and was diagnosed with thalassemia and hemoglobinopathies. Capillary electrophoresis (CE) demonstrated 1.6% of Hb A2, with a minor unknown peak at the initial Z1 zone (1.7%). Identification of abnormal hemoglobin (Hb) using direct DNA sequencing showed a genetic defect causing a δ-globin gene missense mutation at codon 43 (GAG>AAG) causing a glutamic acid to lysine substitution corresponding to Hb A2-Melbourne. The origin of Hb A2-Melbourne in Lao PDR may be similar to a case found in Thailand with the [+ – – – – + +] haplotype. We developed a method that could clearly detect Hb A2-Melbourne and Hb A2-Lampang (HBD: c.142G>A) mutations in a single tube using high resolution melt (HRM) analysis. The HRM analysis is a more effective method for rapid detection than conventional polymerase chain reaction (PCR), as there is no need for a post-PCR step, and no exposure to ethidium bromide. This new method would be a useful addition for the first investigation of a suspected Hb A2 variant in the routine molecular setting.
Acknowledgments
The researchers thank Mr. Dave Patterson (Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand) who is a native English speaker for helpful comments on the manuscript.
Disclosure statement
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.