Some people inherit one sickle cell gene and one other defective hemoglobin gene, resulting in various types of
sickling disorders. These disorders range from mild to severe.
Sickle cell disease (hemoglobin SS disease) occurs when both genes produce
hemoglobin S. This person typically has symptoms of anemia, mild to life-threatening complications, and a
shortened life span.
occurs when a person has one hemoglobin S gene and another gene that causes the
body to produce less hemoglobin than normal. This person may have mild to
severe sickle cell disease.
Hemoglobin SC disease occurs when a person has one hemoglobin S gene and one abnormal
hemoglobin C gene. This person may have generally milder symptoms and a longer
life span than a person with sickle cell disease but still may become seriously
Hemoglobin SE disease occurs when a person has one hemoglobin S gene and one abnormal
hemoglobin E gene. This person may have mild anemia. Most people do not have symptoms.
Hemoglobin SO disease and hemoglobin SD disease occur when a person has one
hemoglobin S gene and one abnormal hemoglobin O or hemoglobin D gene. This
person may experience all sickle cell disease symptoms, ranging from mild to
Natarajan K, et al. (2010). Disorders of hemoglobin structure: Sickle cell anemia and related abnormalities. In K Kaushansky et al., eds., Williams Hematology, 8th ed., pp. 709-741. New York: McGraw-Hill.
Steinberg MH (2016). Sickle cell disease and other hemoglobinopathies. In L Goldman, A Shafer, eds., Goldman-Cecil Medicine, 25th ed., vol. 2, pp. 1095-1104. Philadelphia: Saunders.
Wang WC (2009). Sickle cell anemia and other sickling syndromes. In JP Greer et al., eds., Wintrobe’s Clinical Hematology, 12th ed., pp. 1038-1082. Philadelphia: Lippincott Williams and Wilkins.
ByHealthwise Staff Primary Medical ReviewerE. Gregory Thompson, MD – Internal Medicine Adam Husney, MD – Family Medicine Martin J. Gabica, MD – Family Medicine Specialist Medical ReviewerMartin Steinberg, MD – Hematology