Sickle cell disease (SCD) is a hereditary blood disorder that is caused by an abnormality in the hemoglobin in red blood cells. Hemoglobin is a protein that is found in red blood cells, and it plays an important role in carrying oxygen to all parts of the body.

Hemoglobin

Hemoglobin is the substance that creates the red color of red blood cells. Red blood cells contain a large number of hemoglobin molecules. Hemoglobin can transport oxygen or carbon dioxide through your body in the bloodstream. Oxygen is a very important fuel for the cells in your body. You breathe in the oxygen through your lungs, where it crosses into the bloodstream. In the blood, the oxygen binds to the hemoglobin in the red blood cells. The red bloods cells are transported across the body, delivering oxygen to cells all over the body.
When you have sickle cell disease, your hemoglobin is atypical. This abnormal type of hemoglobin is called hemoglobin S (where the S stands for Sickle cell). The problem is that hemoglobin S (HbS) potentially binds to other HbS within the red blood cell, causing the red blood cell to become abnormally shaped, namely the shape of a sickle. These sickle-shaped red blood cells are less flexible than normal red blood cells and cause problems.