Table 1.
Effect of α-thalassemia on some clinical complications of sickle cell anemia (adapted from Steinberg, 2009).
| Sickle cell disease phenotype | Effect of α-thalassemia |
|||
|---|---|---|---|---|
| Protectivea | Permissiveb | Unrelated | Probably little effect | |
| Survival | + | − | – | − |
| Painful episodes | − | + | − | − |
| Stroke | + | − | − | − |
| Osteonecrosis | − | + | − | − |
| Acute chest syndrome | − | − | + | − |
| Cholelithiasis | + | − | − | − |
| Leg ulcer | + | − | − | − |
| Splenic function | + | − | − | − |
| Growth and development | − | − | + | − |
| Menarche | + | − | − | |
| Priapism | − | + | − | − |
| Splenic sequestration | − | − | − | + |
| HbF | − | − | − | + |
a
“Protective” denotes a reduction in the incidence or prevalence of a phenotype with α-thalassemia.
b
“Permissive” denotes an increased incidence or prevalence of a phenotype when α-thalassemia is present.