Sickle cell trait occurs in approximately 300 million people worldwide, with the highest
prevalence of approximately 30% to 40% in sub-Saharan Africa. Long considered a benign
carrier state with relative protection against severe malaria, sickle cell trait occasionally
can be associated with significant morbidity and mortality. Sickle cell trait is exclusively
associated with rare but often fatal renal medullary cancer. Current cumulative evidence
is convincing for associations with hematuria, renal papillary necrosis, hyposthenuria,
splenic infarction, exertional rhabdomyolysis, and exercise-related sudden death.
Sickle cell trait is probably associated with complicated hyphema, venous thromboembolic
events, fetal loss, neonatal deaths, and preeclampsia, and possibly associated with
acute chest syndrome, asymptomatic bacteriuria, and anemia in pregnancy. There is
insufficient evidence to suggest an independent association with retinopathy, cholelithiasis,
priapism, leg ulcers, liver necrosis, avascular necrosis of the femoral head, and
stroke. Despite these associations, the average life span of individuals with sickle
cell trait is similar to that of the general population. Nonetheless, given the large
number of people with sickle cell trait, it is important that physicians be aware
of these associations.