What is Sickling?
Sickling is when the hemoglobin inside red blood cells sticks or clumps together, causing the cell to become fragile, rigid, and crescent—or sickle—shaped. Take a closer look at how red blood cells become distorted and as well as how these sickled cells can affect your body and cause the symptoms and complications of sickle cell.
Hemoglobin
a protein in red blood cells that helps carry oxygen throughout the body
Normal adult hemoglobin (HbA)
healthy form of adult hemoglobin produced when there is no mutation in the HBB gene and it does not stick together to cause sickling
Hemoglobin Sickle (HbS)
an abnormal form of hemoglobin that can stick together and cause cells to become rigid, sticky, fragile, and sickle-shaped
Polymerization
a process in which smaller molecules combine to create a larger group of molecules called a polymer
Endothelial cells
a layer of cells that line blood vessels
What Causes Sickling?
Each red blood cell is densely packed with hemoglobin proteins. Healthy red blood cells are packed with a form of hemoglobin called normal adult hemoglobin (HbA). HbA looks and functions properly all the time.
In sickle cell, red blood cells are packed with hemoglobin sickle (HbS) proteins. (HbS) proteins are created due to having two copies of an abnormal HBB gene.
These molecules proteins look and work normally in a high-oxygen state (when carrying oxygen to your cells and organs), but they can change to an abnormal shape when they are in low-oxygen state.
This change in shape, (called a conformational change) can cause these HbS molecules to stick to one another. When there are many HbS molecules in a cell, they clump together and form long chains called polymers in a process called polymerization.
The amount of HbS molecules you have compared with other forms of hemoglobin in the cell—and their subsequent polymerization—are the ultimate cause of sickling in red blood cells as well as the associated symptoms and complications of sickle cell.
What Causes Sickling?
Each red blood cell is densely packed with hemoglobin proteins. Healthy red blood cells are packed with a form of hemoglobinHemoglobina protein in red blood cells that helps carry oxygen throughout the body called normal adult hemoglobinNormal adult hemoglobin (HbA)healthy form of adult hemoglobin produced when there is no mutation in the HBB gene and it does not stick together to cause sickling (HbA). HbA looks and functions properly all the time.
In sickle cell, red blood cells are packed with hemoglobin sickleHemoglobin Sickle (HbS)an abnormal form of hemoglobin that can stick together and cause cells to become rigid, sticky, fragile, and sickle-shaped (HbS) proteins. HbS proteins are created due to having two copies of an abnormal HBB gene. These proteins look and work normally in a high-oxygen state (when carrying oxygen to your cells and organs), but they can change to an abnormal shape when they are in low-oxygen state.
This change in shape (called a conformational change) can cause these HbS molecules to stick to one another. When there are many HbS molecules in a cell, they clump together and form long chains called polymers in a process called polymerizationPolymerizationa process in which smaller molecules combine to create a larger group of molecules called a polymer.
The amount of HbS molecules you have compared with other forms of hemoglobin in the cell—and their subsequent polymerization—are the ultimate cause of sickling in red blood cells as well as the associated symptoms and complications of sickle cell.
Check out the video to see how sickle cell occurs and uncover how sickling can cause silent, progressive damage to the body.
Mechanism of Sickle Cell Disease Mechanism of Sickle Cell Disease
Mechanism of Sickle Cell Disease Mechanism of Sickle Cell Disease
Consequences of Sickling
Sickled red blood cells are very rigid and sticky and can have difficulty moving through small blood vessels. They can slow or block blood flow in these blood vessels (known as vaso-occlusion), preventing oxygen from properly circulating in the body as pictured in the image below. Blockages and broken down red blood cells also cause damage to blood vessels (known as vasculopathy), as well as the cells that line them (known as endothelial cellsEndothelial cellsa layer of cells that line blood vessels). Additionally, sickled red blood cells are fragile and can break down prematurely (known as hemolysis), lasting only 10 to 20 days throughout the body, compared to 90 to 120 days for healthy red blood cells. This shorter lifespan can create a shortage of red blood cells throughout the body, leading to complications such as anemia and fatigue.
Blockages can lead to unpredictable complications like pain crises or stroke. Repeated blockages, damage to the blood vessels, and hemolysis over time can lead to progressive chronic complications, including organ damage and even organ failure.
I'm still here. I'm still fighting. And I want others to know that they can do that, too."
I'm still here. I'm still fighting. And I want others to know that they can do that, too."
KEVIN
Living With Sickle Cell, President of Uriel Owens Sickle Cell Disease Association of the Midwest
What Can You Do?
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Recognizing how sickle cell impacts your life may help spark important discussions with others to bring changes in your care and the care of your loved ones. How does sickle cell affect you?