Molecular and hematological profiles of hemoglobin EE disease with different forms of α-thalassemia

We describe hematologic and DNA characterization of hemoglobin (Hb) E homozygote with various forms of α-thalassemia in Thai individuals. Altogether, 131 unrelated adult subjects with Hb EE at routine Hb analysis were studied. Forty-two cases were found to carry α-thalassemia with ten different genotypes. These included 21 cases with α⁺-thalassemia heterozygote (–α^3.7/αα), one case with α⁺-thalassemia heterozygote (–α^4.2/αα), six cases with Hb Constant Spring heterozygote (α^CSα/αα), four cases with homozygous α⁺-thalassemia (–α^3.7/–α^3.7), one case with homozygous α⁺-thalassemia (–α^4.2/–α^4.2), two cases with compound α⁺-thalassemia/Hb Constant Spring (–α^3.7/α^CSα), one case with compound α⁺-thalassemia/Hb Paksé (–α^3.7/α^PSα), four cases with α⁰-thalassemia heterozygote (––^SEA/αα), and, unexpectedly, two cases with compound α⁰-thalassemia/α⁺-thalassemia [(––^SEA/–α^3.7) and (––^SEA/–α^4.2)]. The hematological expression of these Hb E homozygotes with various forms of α-thalassemia was presented comparatively with those of the 89 cases of pure Hb E homozygotes. Overlapping levels of Hb E, Hb F, and other hematological parameters were observed which did not predict clinical severity, indicating a need for α-globin gene analysis for accurate diagnosis and improved genetic counseling.