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 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.
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