Interaction of an α-globin Gene Triplication with Other Forms of Thalassemia or Hemoglobinopathy in Northern Thailand.

There was only one report of α-globin gene triplication identified in Northern Thailand. Moreover, the genotype and phenotype associated with α-globin gene triplication and its interactions with other types of thalassemia or hemoglobinopathy remain unclear. Therefore, this study aimed to analyze the genotype and phenotype of α-globin gene triplication and its co-inheritance forms found in this area.Blood samples anti-coagulated with ethylenediamine tetra acetic acid (EDTA) and the data of red cell indices were obtained from hospitals in Northern Thailand. The molecular analysis for detection of αααanti3.7 and αααanti4.2 triplications was performed using a single-tube multiplex-PCR. The β- and α-globin gene mutations were also analyzed using targeted next-generation sequencing (NGS).The α-globin gene triplication was found in 8 of 2,078 (0.38%) samples classified into five different genotypes. A microcytic-hypochromic anemia (MCV < 80 fL and MCH < 27 pg) was not found in samples with αααanti3.7 triplication alone while it was observed in the other genotypes. Moreover, the samples who coinherited with αααanti3.7 triplication and β-thalassemia had the lowest levels of MCV and MCH.The clinical and hematological features of the α-globin gene triplication varied when interacting with other forms of thalassemia or hemoglobinopathy. This information should be provided at genetic counseling and prenatal thalassemia diagnosis. However, the detection rate (0.38%) among referred samples may underestimate population prevalence, as it excludes individuals with normal red cell indices and hemoglobin levels. Thus, further large-scale population studies along the Northern Thailand are required to validate these findings.