Be aware

Learning about sickle cell disease can help you have informed, productive conversations with your doctor. Generation S is here to give you information to help you be your own best advocate!

The sickle cell story starts with genetics

Sickle cell disease is an inherited blood disorder. That means if someone has sickle cell disease, it was passed down through genes from their birth parents.

Genes are the code that builds the body. For example, eye color is determined by a set of genes from birth parents. Another set of genes determines how red blood cells are made and how they work. Those genes are called the hemoglobin [hee-muh-gloh-bin] genes, named after the hemoglobin protein in red blood cells that helps carry oxygen through the body. The graphic below shows how HbSS, the most common type of sickle cell disease, can be passed from birth parents to their children. 

Different genes, different types of SCD

The term “sickle cell disease” actually refers to a group of blood disorders caused by “sickled” hemoglobin, HbS. HbS is what all people with sickle cell disease have in common. There are, however, different types of sickle cell disease. The specific type of sickle cell disease that someone has depends on the kind of hemoglobin, in addition to the abnormal HbS gene, they inherit from their birth parents.

HbSS, which comes from both birth parents passing on HbS, is the most common type of sickle cell disease, but is not the only type. That is because in addition to HbS, there are other changes to the hemoglobin gene that birth parents can pass on to their children. Two examples are HbC and Hbβ-thalassemia [thal-uh-see-mee-uh]. Like HbS, those genes limit how much oxygen red blood cells can carry through the body.

Any combination of HbS passed on with another hemoglobin gene, such as HbC and Hbβ-thalassemia, can result in sickle cell disease.

Diagram of different sickle cell disease types

You’re not alone

So many others are impacted by sickle cell disease. In fact, sickle cell disease is the most common genetic blood disorder in the United States.

Facts about sickle cell disease

People of African ancestry make up 90% of the population with sickle cell disease in the United States. However, sickle cell disease also affects people of Hispanic, South Asian, Southern European, and Middle Eastern ancestry.


 Sickle cell disease facts

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