What causes the red blood cells to be sickle-shaped?
Genes tell the body how to make proteins. An error in the DNA spelling of the gene for hemoglobin causes the hemoglobin protein to be shaped abnormally. People with SCD have spelling errors in both copies of the hemoglobin gene. Everyone with SCD has a specific spelling error that causes the sickle shape in at least one copy. Different spelling errors in the second copy of the hemoglobin gene cause the different forms of SCD. People with SS have the sickle cell gene change in both copies. People with hemoglobin SC have a gene change that makes another form of abnormal hemoglobin (type C). People with hemoglobin S-beta thalassemia have a different gene error that causes abnormal hemoglobin.
