What Is Sickle Cell Disease?
Sickle cell disease is an inherited blood disorder. People with sickle cell disease inherit an abnormal gene from their biological (birth) parents which causes abnormal hemoglobin to form in their red blood cells. Hemoglobin is the protein in red blood cells that carries oxygen to different parts of the body. Sickle cell disease affects the blood’s ability to deliver oxygen efficiently.
Normal red blood cells are smooth and flexible discs that look like the letter O and move easily through your blood vessels. In contrast, sickle cells are stiff, sticky, and often shaped like the letter C. Sickle cells tend to cluster together and stick to the lining of blood vessels, creating blockages that stop the movement of healthy, oxygen-carrying blood. This blockage decreases oxygen delivery to the tissues, which can cause pain, organ dysfunction, and other complications including:
- Kidney failure
- Heart failure
- Stroke
- Infection
- Blood clots
What Causes Sickle Cell Disease?
Sickle cell disease is caused by a gene that doesn’t work properly. It is inherited from an individual’s biological (birth) parents. People who have two parents with the sickle cell trait in their genes have a 1 in 4 chance of developing sickle cell disease.
The abnormal gene affects red blood cell formation. Instead of being round and flexible, red blood cells in individuals with sickle cell disease have a banana-like shape which can slow or block blood flow, causing pain and other health problems.
Who Is at Risk for Developing Sickle Cell Disease?
Sickle cell disease affects approximately 100,000 individuals in the U.S. It is most common among African Americans and people of African descent. It is also common in Hispanic Americans, and people of Middle Eastern, Asian, Indian, and Mediterranean descent.
What Are Symptoms of Sickle Cell Disease?
Symptoms may develop early in infancy. Some people with sickle cell disease have mild symptoms; others develop more serious health complications.
Pain is the main symptom of sickle cell disease. Vaso-occlusive crises (VOC) or vaso-occlusive episodes (VOE) are acute pain caused by sickled cells getting stuck and blocking blood flow. Pain is often frequent and can be extreme.
Other symptoms include:
- Anemia, which causes fatigue, weakness, and paleness. Anemia happens when red blood cells die early and there aren’t enough healthy red blood cells to carry oxygen throughout the body.
- Yellowing of the skin or whites of the eyes (jaundice)
- Painful swelling of the hands and feet
How Is Sickle Cell Disease Diagnosed?
Children born in the United States are screened at birth for sickle cell disease. For those not screened at birth, sickle cell disease can be diagnosed by a blood test.
Sickle cell disease can be identified before birth by testing a sample of amniotic fluid or placenta tissue.
How Is Sickle Cell Disease in Children Treated?
Dana-Farber/Boston Children's Cancer and Blood Disorders Center is an international leader in improving treatment and quality of life for children affected by sickle cell disease. Through our Sickle Cell Disease Program, children with sickle cell disease have access to world-renowned pediatric hematologists, top-rated nursing care, and the latest treatment options, including:
- Hydroxyurea
- Stem cell transplantation
- Gene therapy
Learn more about sickle cell disease in children and treatment options on the Boston Children's Hospital website.
How Is Sickle Cell Disease in Adults Treated?
Treatments may help people manage the symptoms or complications caused by sickle cell disease.
- Patients may take medication to reduce pain caused by sickle cell disease.
- Other medications may prevent or decrease sickled cells from sticking together and blocking blood vessels.
- Some medications may help prevent infection or minimize organ damage.
- Red blood cell transfusions help increase the number of normal red blood cells in the body.
Stem cell transplant and gene therapy offer the possibility of a cure for sickle cell disease.
Stem Cell Transplant for Sickle Cell Disease
A bone marrow/stem cell transplant is a potentially curative treatment. A stem cell transplant relies on a donor to provide healthy stem cells that can form into healthy blood cells and the immune system. The donor needs to be a full or partial match with the patient; often this is a sibling. Not every patient with sickle cell disease will have a matching donor.
Our Adult Stem Cell Transplantation Program provides stem cell transplants to sickle cell patients with a full match.
Gene Therapy for Sickle Cell Disease
Gene therapy is a way of treating disease by changing the genetic instructions within an individual’s cells. When a gene is missing or doesn’t work correctly, it can cause disease in the body. Gene therapy aims to fix the faulty or missing gene to treat a disease.
Gene therapy is a complex and lengthy treatment process that alters genes in a patient’s stem cells to produce healthy hemoglobin that allows cells to flow normally throughout the body. By boosting healthy red blood cells, gene therapy stops patients’ complications of sickle cell disease.
Gene therapy is FDA-approved for patients 12 years and older with sickle cell disease who experience repeated vaso-occlusive crises (VOCs).
Learn more about gene therapy in adults.
Young adults may be evaluated at the Dana-Farber/Boston Children's Gene Therapy Program.