β-hemoglobinopathies are inherited hemoglobin (Hb) disorders caused by mutations in the β-globin gene, resulting in quantitatively reduced (β+-thalassemia) or absent (β0-thalassemia) β-globin chain synthesis and qualitative β-globin chain defect called structural β-globin chain variant. The gene discussed is GSTM1; the disease is thalassemia.