Sickle Cell Disease

Normal hemoglobin is called hemoglobin A (A for adult). A person who has sickle cell makes a different kind of hemoglobin called hemoglobin S (S for sickle). This abnormal hemoglobin causes the red blood cells to change their shape. Instead of being round, the red blood cell shape looks like a banana or a sickle (a hand tool used to cut wheat or tall grass). This sickle shape of the red blood cells gives sickle cell disease its name.

As a result of the abnormal shape, the red blood cells become hard and sticky, causing them to have trouble moving through small blood vessels. When they clog up these blood vessels, blood cannot bring oxygen to the tissues. This causes pain and eventually damages the tissue.

There are several types of sickle cell disease:

• Hemoglobin SS. This occurs when a child inherits two sickle globin genes; one from the mother and one from the father. This is the most common form of sickle cell disease. 
• Hemoglobin SC. This occurs when a child inherits one sickle globin gene (S) from one parent and one globin gene C (another type of abnormal hemoglobin) from the other parent.
• Hemoglobin S beta thalassemia. This occurs when a child inherits one sickle globin gene (S) from one parent and beta thalassemia (another type of anemia) from the other parent. 
• Hemoglobin SD, hemoglobin SE and hemoglobin SO. These occur when a child inherits one sickle cell gene (S) from one parent and one abnormal hemoglobin gene (D, E or O) from the other parent. These are rarer forms of sickle cell disease.

Children with sickle cell disease may experience the following symptoms or complications:

• Anemia. Anemia occurs when there are not enough red blood cells or hemoglobin in the bloodstream to move sufficient oxygen from the lungs to the rest of the body. Sickle cell disease can cause anemia.
• Jaundice. Jaundice is yellowing of the skin and whites of the eyes. This occurs because sickle cells are not as stable as normal red blood cells and break down very quickly. The breakdown product of red blood cells is called bilirubin, and excess bilirubin leads to jaundice.
• Pain crisis. This occurs when sickle cells stick together to the blood vessel walls. These cells block blood flow and cause severe pain. Pain is a common symptom.  
• Acute chest syndrome. This symptom involves the lungs and is a dangerous complication of sickle cell disease that requires immediate medical attention.
• Splenic sequestration. This complication occurs when red blood cells become trapped in the spleen.
• Stroke. This complication occurs most frequently in those who have the SS type of sickle cell disease. It can lead to devastating consequences.

Every child with sickle cell disease experiences different symptoms and complications.

Sickle cell trait is not the same as sickle cell disease. This condition occurs when a child inherits only one sickle globin gene (S) from one parent and a normal beta globin gene from the other parent. Sickle cell trait cannot develop into sickle cell disease. A child with sickle cell trait may be referred to a hematologist early in life to confirm and learn more about the diagnosis. Patients with sickle cell trait should be able to lead normal, healthy lives. They may need genetic counseling when they become parents to determine the risk of having a child with sickle cell disease.

Diagnosis of Sickle Cell Disease

Doctors at Riley at IU Health often diagnose sickle cell disease through a newborn screening test, which is performed on every child born in Indiana. Newborn screening allows doctors to identify those with sickle cell disease as early as possible. Early prevention and education improves the quality of lives of children. Children with a positive screen are referred to a hematologist, a doctor who specializes in the condition. The hematologist will do additional testing to confirm the diagnosis and identify the type of sickle cell disease.