HBA2 and thalassemia: In Indonesian Guideline for Management of Thalassemia (2018), possibility of thalassemia traits is identified by HbA2 examination: an HbA2 level between 3.6 and 4.2% suggests mild β+-thalassemia and levels between 4 and 9% suggest heterozygote β0-thalassemia and severe β+-thalassemia [7].