| Details | Sickle cell disease (SCD) and its variants are genetic disorders resulting from the presence of a mutated form of hemoglobin, hemoglobin S (HbS)[1,2] (see the image below). The most common form of SCD in North America is homozygous HbS disease (HbSS), an autosomal recessive disorder most oftren found in people of African and Mediterranean ancestry (see Pathophysiology). SCD causes significant morbidity and mortality, although the severity, frequency of crisis, degree of anemia, and organ systems involved vary considerably from individual to individual. |