Table 1.

Types of Sickle Cell Disease

Condition	Condition acronyms	Inheritance/Clinical manifestations
Homozygous sickle cell disease, sickle cell disease SS, or sickle cell anemia	HbSS or SCD-SS	Hemoglobin S gene is inherited from both parents.
		Usually the most severe form of sickle cell disease.
Sickle hemoglobin C disease, hemoglobin HbSC disease or, sickle cell disease SC	HbSC or SCD-SC	Hemoglobin S gene is inherited from one parent and hemoglobin C gene is inherited from the other parent.
		This is usually a milder form of the disease.
Sickle beta thalassemia disease: two major types		Hemoglobin S gene is inherited from one parent and the beta thalassemia gene is inherited from the other parent.
1. Sickle beta zero thalassemia	HbS βo-thal or SCD-S βo-thal	People with HbS βo-thal usually have a more severe form; people with HbS β+- thal usually have a milder form.
2. Sickle beta plus thalassemia	HbS β+-thal or SCD-β+-thal
Rarer type examples:		In these rarer types a person inherits one sickle cell gene from one parent and one abnormal hemoglobin gene from the other parent.
Hemoglobin SD disease or sickle cell disease SD	HbSD or SCD-SD
Hemoglobin SE disease or sickle cell disease SE	HbSE or SCD-SE	The severity of these rarer types of the disease varies. For example, while HbSE parallels that of HbS β+-thal, HbSOArab and HbSCHarlem often have severe disease symptoms and complications similar to people with HbSS. HbS Lepore and HbSD have milder symptoms.
Hemoglobin SO Arab disease or Sickle cell disease SO Arab	HbSOArab or SCD-SOArab
Hemoglobin SC Harlem or Sickle cell disease SC Harlem	HbSCHarlem or SCD-SCHarlem
Hemoglobin sickle Lepore or Sickle cell disease Lepore	HbS Lepore or SCD-S Lepore

Note: Adapted from: Pass et al. (2000).