In Southeast Asia, homozygous β-thalassemia, β-thalassemia/hemoglobin E (HbE, HBB: c.79G > A; p.Glu27Lys), hemoglobin H (HbH; compound heterozygosity for α0-thalassemia and α+-thalassemia), hemoglobin H-Constant Spring (HbH-CS; compound heterozygosity for α0-thalassemia), and HbCS (HBA2: c.427T > C; p.Ter143GlnextTer31) are among the most common thalassemia syndromes [1]. Here, CS is linked to thalassemia.