Disease Information

Hematologic Disorders: Sickle Cell Disease

Alternate Names: sickle cell anemia, hemoglobin SC disease, sickle beta thalassemia disease

Definition

Sickle cell disease is a genetic blood disorder that affects the hemoglobin within the red blood cells.  Hemoglobin is the main ingredient in red blood cells.  Hemoglobin helps red blood cells carry oxygen from the lungs to other parts of the body.  Normal red blood cells have hemoglobin A.  Hemoglobin A helps keeps red blood cells soft and round; it allows them to be flexible and flow easily through small blood vessels. People with sickle cell disease have hemoglobin S (also called sickle hemoglobin) in their red blood cells.  Under certain circumstances, hemoglobin S causes the blood cells to become hard and form a sickle (or banana) shape. Sickle shaped hemoglobin can block small blood vessels causing complications such as, pain, organ damage, sequestration or stroke.

There are several different types of sickle cell disease.  Sickle cell disease is the name for a group of disorders that all have predominantly sickle hemoglobin. The most common types of sickle cell disease within the United States are:


Incidence

In the United States, approximately one in 375 African-Americans is born with sickle cell disease each year.


Influencing Factors

Genetics


Survival Rates

Patients with sickle cell disease can have many clinical complications affecting their health and survival. Earlier studies from the 1980s suggested that patients with homozygous sickle cell disease (HbSS) had a life expectancy in the mid-40s. However, with early diagnosis and management, coupled with comprehensive care and more therapeutic options, the life expectancy in sickle cell disease is increasing.


Treatment Strategies

Chronic Red Blood Cell Transfusions. Chronic red blood cell transfusions are used as a treatment for various complications of sickle cell disease. Transfusions are the major treatment for cerebrovascular accidents (stroke) in children with sickle cell disease. With chronic transfusions, blood is given every three to four weeks. Complications of chronic red blood cell transfusions include iron overload, infection, antibody formation, and transfusion reactions.

Hydroxyurea. All infants are born with fetal hemoglobin (HbF) in their blood cells; however, soon after birth the amount of HbF rapidly decreases. Hydroxyurea is a medication taken by mouth once a day to help increase the body’s production of HbF, thereby reducing sickling and many of the major complications of sickle cell disease. 

Bone Marrow Transplantation. Bone marrow (or stem cell) transplantation is the only cure for sickle cell disease. The cure was first performed successfully in 1983, when a St. Jude patient with leukemia and sickle cell disease received a bone marrow transplant. The procedure cured both diseases.  Red blood cells are made in the bone marrow. In a person with sickle cell disease, the bone marrow produces hemoglobin S instead of hemoglobin A. During a transplant, the patient’s bone marrow is replaced with marrow from a person who does not have sickle cell disease. Even though bone marrow transplant is a cure for sickle cell disease, its use is limited because of the difficulty in finding a matched donor, and the complications associated with transplant.


Current Research

St. Jude Children's Research Hospital has one of the largest and most active Sickle Cell Disease Programs in the nation. St. Jude treats approximately 800 children per year with sickle cell disease.  St. Jude has several labs, which perform various research on sickle cell disease. These labs perform basic science and translational research. Basic science involves theoretical research which is conducted in the lab. Translational research brings the research from the lab to the patient.

In 2008, the National Heart, Lung and Blood Institute named St. Jude as one of 12 institutions nationwide to participate in the Basic and Translational Research Program (BTRP) on sickle cell disease. The BTRP funded 2 projects at St. Jude under this program.

St. Jude is also recognized for their research for clinical trials. Clinical trials are aimed at finding better ways to treat children with sickle cell disease. Some of the major clinical trials at St. Jude include:

 

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