Are there different types?

Yes, there is HbSS, HbS, HbSD, HbSE, and HbSO.

HbSS- Inherit a sickle gene S and abnormal hemoglobin trait C. This form of SCD is mild.

HbS- Inherit sickle gene S and one gene for Beta Thalassemia, a type of anemia. This form of SCD is mild.

HbSD, HbSE, HbSO- Inherit sickle gene S and hemoglobin gene D, E, or O. These forms aren't as common and the severity ranges from person to person.