Development of a High Resolution Melting Curve Analysis for the Detection of Hemoglobin δ-Chain Variants in Thailand and Identification of Hb A2-Walsgrave [codon 52 (GAT>CAT), Asp→His; HBD:c.157G>C] in a Pregnant Woman from Southern Thailand.

Abstract

Background: Delta-chain (δ-chain) variants are a group of rare hemoglobin (Hb) variants resulting from mutations within the δ-globin gene. Although quantification of Hb A2 levels is a useful screening tool for the beta-thalassemia trait, the coinheritance of a δ-globin gene mutation can lead to misinterpretation of diagnostic results. Objective: To identify an unreported Hb A2 variant in Thailand and to develop a high resolution melting (HRM) curve assay for the four δ-globin chain variants found in the Thai population. Materials and Methods: Allele-specific polymerase chain reaction (ASPCR) was used to analyze a total of 18 DNA samples for Hb variants comprising 10 wild-type controls, 4 Hb A2-Melbourne, 1 Hb A2-Lampang, 2 Hb A2-Kiriwong, and an unknown variant via HRM assays. Results: The unreported Hb A2 variant in Thailand was found to be Hb A2-Walsgrave resulting from δ-globin gene mutation at codon 52 (GAT>CAT). This was also confirmed using ASPCR. In addition, we demonstrated that the HRM curve profile for Hb A2-Melbourne, Hb A2-Lampang, Hb A2-Walsgrave, and Hb A2-Kiriwong could be identified so as to distinguish the mutant alleles from one another and from wild-type alleles. Conclusion: This HRM assay detected both known and unknown mutations with simultaneous differentiation between heterozygous and homozygous alleles on a polymerase chain reaction fragment spanning four of the δ-globin variants found in Thailand. This assay may help to support the prevention and control of thalassemias and hemoglobinopathies in Thailand.

• Authors: Thanet Prajantasen, Patcharawadee Prayalaw, Sitthichai Panyasai, Sukanya Binlee, Supang Nongnuan
• Journal: Genetic testing and molecular biomarkers (Genet Test Mol Biomarkers) Vol. 25 Issue 6 Pg. 426-433 (Jun 2021) ISSN: 1945-0257 [Electronic] United States
• PMID: 34152843 (Publication Type: Case Reports, Journal Article, Observational Study)

Chemical References

• Biomarkers
• Hemoglobins, Abnormal
• gamma-Globins
• hemoglobin A2-Melbourne
• Hemoglobin A2

Topics

• Biomarkers (blood)
• DNA Mutational Analysis (methods)
• Female
• Hemoglobin A2 (genetics, isolation & purification)
• Hemoglobins, Abnormal (genetics, isolation & purification)
• Heterozygote
• Homozygote
• Humans
• Mutation
• Pregnancy
• Pregnancy Complications, Hematologic (blood, diagnosis, genetics)
• Thailand
• Thalassemia (blood, diagnosis, genetics)
• Young Adult
• gamma-Globins (genetics)