Two variants. Hemoglobin sc is present in people who have two variants of the beta chain of hemoglobin. One gene has sickle cell variant and the other gene has hemoglobin c variant. There disease is more sever than hb s trait, but less severe than hb s disease.
Sickle+hemoglobin C. Hemoglobin sc disease is where one of your beta-hemoglobin genes carries the mutation for sickle cell disease and the other carries the mutation known as hemoglobin c. On average, patients with hemoglobin sc disease have milder symptoms than do those with sickle cell disease, though it is possible to have sickle crises with this disease.