GSTM1 and hemoglobin measurement: This study aimed to investigate the effects of α-globin gene mutations on clinical phenotype and hematological parameters in pediatric patients with homozygous β-thalassemia, β-thalassemia/Hb E disease, β-thalassemia carriers, homozygous Hb E, and Hb E traits at Phramongkutklao Hospital, a tertiary care center for thalassemia patients across Thailand.