General Principles

• SCD is a group of hereditary Hgb disorders in which Hgb undergoes a sickle shape transformation under conditions of deoxygenation.
• The most common are homozygous sickle cell anemia (Hgb SS) or other double-heterozygous conditions (Hgb SC, Hgb S–β⁰, or Hgb S–β⁺ thalassemia).
• Newborn screening programs for hemoglobinopathies are available throughout the US and identify most patients in infancy.
• In the US, the incidence of SCD is approximately 1 in 625 births.
• Sickle cell trait is present in 7%–8% of African Americans. It is generally considered to be a benign carrier state, but high-altitude hypoxia is associated with splenic infarction, whereas intense physical exertion has been associated with sudden death and rhabdomyolysis.
• Sickle cell trait has been associated with an increased risk of pulmonary embolism, proteinuria, and CKD. Minimizing other risk factors for kidney disease is likely to benefit patients at risk.