

Red blood cells can become misshapen into a “sickle shape,” like a crescent moon.

Healthy red blood cells

Sickled red blood cells
Sickle cell disease can lead to serious complications over time, like organ damage.
Sickle cell disease can impact quality of life and may lead to serious complications that can impact long-term health.
In sickle cell disease, there is a change in one of the genes that makes a part of hemoglobin (Hb). Hemoglobin is a protein in red blood cells. This genetic change affects how Hb behaves.
| Type of sickle cell disease | How common is it?* |
|---|---|
| HbSS | About 75% of people with sickle cell disease |
| HbSC | About 18% of people with sickle cell disease |
| HbS beta-plus thalassemia | About 4% of people with sickle cell disease |
| HbS beta-zero thalassemia | About 2% of people with sickle cell disease |
*A large international study of 674 people with sickle cell disease published in 2011 looked at the genetic types in people of mainly African descent living in the Americas and the UK.
No matter the type, all forms of sickle cell disease are considered serious. This is because all forms of sickle cell disease can lead to life-threatening complications.