Further Identification of Hb G-Coushatta [β22(B4)Glu→Ala (GAA→GCA)] in Thailand by the Polymerase Chain Reaction-Single-Strand Conformation Polymorphism Technique and by Amplification Refractory Mutation System-Polymerase Chain Reaction

Abstract

Thalassemias and hemoglobinopathies are very common among Southeast Asian populations, particularly in Thailand, where it is estimated that nearly 30% of the population carries at least one such disorder. Moreover, the heterogeneity of different mutant α- and β-globin alleles contributes to the complexity in diagnosis and proper management, as more than 60 thalassemia syndromes and hemoglobinopathies have been described. Herein we report a further case of Hb G - Coushatta [β22(B4)Glu→Ala (GAA→GCA)] (also known as G - Saskatoon, G - Hsin Chu and G - Taegu) in a Thai family in which the mother was found to have an unusual hemoglobin (Hb) anomaly in combination with Hb E [β26(B8)Glu→Lys, GAG→AAG]. We applied our recently described polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique to scan the β-globin genes and found an aberrant pattern in exon 1. The molecular analysis by direct genomic sequencing successfully identified the nucleotide mutation (codon 22, GAA→GCA), and a novel amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) for this variant is described.

Keywords:

• Hb G-Coushatta
• Hb E/ β-thalassemia (thal)
• Hemoglobin (Hb) variant
• Polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP)