Table 1.
Clinically Significant Hemoglobinopathies (Modified from [2])
| Genetic alteration | Epidemiology | Clinical presentation | |
|---|---|---|---|
| α-chain disorders | |||
| α+-thalassemia trait | Reduced globin chain production [αα/α-] | Worldwide | Asymptomatic |
| α0-thalassemia trait | Reduced globin chain production [αα/--] | Worldwide | Mild anemia |
| α-thalassemia Hemoglobin H disease (HbH) | Reduced globin chain production [α-/--] | Worldwide | Chronic hemolytic anemia; transfusions required to support life. |
| α-thalassemia Hemoglobin Constant Springs (HbCS) | Insertion of additional amino acids on one α-globin chain [αCS-/--] | Southeast Asia, China | Mild anemia |
| α-thalassemia Hemoglobin Barts | Reduced globin chain production [--/--] | Worldwide | Incompatible with extra-uterine life |
| β-chain disorders | |||
| β-thalassemia minor/trait | Reduced expression of one β-globin gene | Worldwide | Typically asymptomatic |
| β-thalassemia major | Reduced expression of both β-globin genes | Worldwide | Significant anemia leading to transfusion dependence |
| Hemoglobin C | Glu → Lys at position 6 of β-globin | West Africa | Mild anemia (HbCC); asymptomatic when inherited as hemoglobin C trait (HbAC) |
| Hemoglobin E | Glu → Lys at position 26 of β-globin | Southeast Asia | Mild anemia |
| Hemoglobin S | Glu → Val at position 6 of β-globin | Central/West/East Africa; South Asia; Arabian peninsula | Sickle-cell disease (HbSS, SC Sβ0Thlassemia); asymptomatic when inherited as sickle cell trait (HbAS) |