What Is Sickle Cell Disease?

Sickle cell disease is an inherited genetic blood disorder. People with sickle cell disease make an abnormal type of hemoglobin, which is the protein in red blood cells that carries oxygen throughout the body. This abnormal hemoglobin prevents organs and tissue from receiving enough oxygen.

Healthy red blood cells with normal hemoglobin are round and move easily throughout the body. Sickle cell disease causes red blood cells to develop shaped like a farm tool called a sickle (or like the letter C).

Sickled red blood cells are also hard and sticky, so they clump together. These clumps cannot easily move through blood vessels and they can get stuck, blocking blood flow. These blockages can cause pain or organ damage.

Sickle Cell Symptoms

Most children will start having symptoms during the first year of life, often around 5 months old. Symptoms may be mild or severe, and can include:

Anemia: The most common symptom, anemia can make your child pale and tired. Lack of healthy red blood cells causes anemia.
Jaundice: Yellowing of the skin, eyes and mouth (jaundice) is another common symptom. The yellow color comes from a substance called bilirubin that is released when red blood cells die. Sickle cells die sooner than healthy cells.
Sickle cell pain: When sickle cells move through small blood vessels, they can get stuck and block blood flow, causing pain. Sudden pain can happen anywhere, but most often occurs in the chest, arms and legs. Babies and young children may have painful finger and toe swelling.
Acute chest syndrome: Sickle cells can stick together and block oxygen flow in the tiny vessels in the lungs, causing acute chest syndrome. This often happens suddenly, when the body is under stress from infection, fever or dehydration. It looks like pneumonia, and can include fever, pain and a violent cough.
Splenic sequestration (pooling): Normally, the spleen helps filter infections out of the blood. But sickle cells get stuck in the spleen and die, which can enlarge the spleen and cause pain. This may cause a sudden drop in hemoglobin that requires immediate treatment.
Infections: Children with sickle cell are at higher risk for infections. Sickle cells can damage the spleen, making it harder to fight off infections.

Sickle Cell Causes and Risk Factors

Sickle cell disease is inherited when a child inherits two abnormal hemoglobin genes, one from each parent. Once parents have a child with sickle cell disease, there is a 25 percent chance that any future child they have will be born with the condition. There is a 50 percent chance that any future child will be a carrier, like the parents.

Sickle cell disease is the most common genetic disease among African Americans. It mainly affects people whose families came from Africa, and Hispanics whose families are from the Caribbean, but it can affect people of any race or ethnicity. The sickle cell trait has also been found in people whose families are from the Middle East, India, Latin America and the Mediterranean, as well as in Native Americans.

Sickle cell types

The hemoglobin S gene causes sickled cells to form. If a person inherits one copy of the hemoglobin S gene and one healthy hemoglobin gene, that person is a carrier of the sickle cell trait, but likely would not experience symptoms. People with sickle cell disease inherit two abnormal hemoglobin genes, including at least one copy of the hemoglobin S gene.

There are different types of sickle cell disease, based on the different genetic hemoglobin defects. Types include:

Hemoglobin SS (sickle cell anemia): This is the most common and most severe type of sickle cell disease, and it usually causes the most symptoms. Inheriting two copies of the hemoglobin S gene causes sickle cell anemia.
Hemoglobin SC: The second most common type of sickle cell disease, Hemoglobin SC disease is similar to sickle cell anemia but less severe. People with this type usually have higher hemoglobin counts and milder symptoms.
Hemoglobin S beta zero thalassemia: This type is similar to sickle cell anemia and symptoms can be severe. Inheriting one hemoglobin S gene and one beta zero gene, which prevents production of normal hemoglobin, causes sickle beta zero thalassemia.
Hemoglobin S beta+ thalassemia: This form of sickle cell is characterized by a reduced amount of hemoglobin and fewer symptoms. The beta plus gene causes the body to produce less hemoglobin.
Hemoglobin SD and Hemoglobin SE: These types are rare and usually have milder symptoms.

Sickle Cell Diagnosis

Most states check newborn babies for abnormal hemoglobin as part of routine newborn screening tests. These tests identify serious, life-threatening diseases.

If the screening shows signs of sickle cell disease, doctors may perform a blood test called hemoglobin electrophoresis. This test will show if your child has sickle cell trait or any diseases linked to the sickle cell gene.

Sickle Cell Disease Treatment

Children with sickle cell disease are living better lives because of advances in research and treatment. Your child will see one of our hematologists, doctors who specialize in treating children with blood disorders.

We focus on providing disease-modifying therapy — treatment that alters the course of the disease — instead of only treating the symptoms of sickle cell. These therapies may provide your child with a better quality of life:

Hydroxyurea: This medication helps blood cells remain round and flexible instead of sickle cell-shaped. Studies have shown hydroxyurea decreases pain crises, acute chest syndrome and the need for blood transfusions.
Chronic blood transfusion therapy: This treatment dilutes the sickle hemoglobin (or HbS) with normal hemoglobin to treat chronic pain, acute chest syndrome and other emergencies.
Bone marrow or stem cell transplant: A transplant can provide a cure for sickle cell disease. The procedure replaces abnormal blood cells with healthy stem cells from a donor, stopping the body’s production of diseased cells. Our doctors are some of the most experienced in the country at performing transplants for sickle cell disease.