Sickle Cell Disease

What Is Sickle Cell Disease?

 

Sickle cell disease (SCD) is the most common inherited blood disorder. That means it’s passed down through families. You’re born with SCD. It’s not something you catch or develop later in life.

Sickle cell disease is also known as:

  • HbS disease
  • Hemoglobin S Disease
  • SCD
  • Sickle cell disorders
  • Sickling disorder due to hemoglobin S

The disease gets its name because when you have SCD, your red blood cells look like a sickle, which is a C-shaped farm tool.

Red blood cells contain a molecule called hemoglobin, which carries oxygen throughout the body. In a healthy person, hemoglobin is smooth, round, and flexible. That allows red blood cells to glide easily through your bloodstream. But if you have SCD, the hemoglobin’s shape is abnormal. That causes red blood cells to become rigid and curved. The odd-shaped cells block blood flow. It’s dangerous and can cause extreme painanemia, and other symptoms.

About 100,000 people in the United States have sickle cell disease. Most of them are African American.

Sickle Cell Disease Symptoms

Babies born with SCD usually show symptoms at around 5 months of age. Symptoms vary from person to person and change over time. Symptoms can include:

  • Anemia. Sickle cells are more fragile than normal red blood cells and tend to die in 10-20 days. Normal cells live for about 120 days. This causes a shortage of red blood cells, known as anemia. There aren’t enough red blood cells to carry oxygen around the body, so it brings on fatigue.
  • Pain crises. These bouts of pain are a major symptom of sickle cell disease. Sickle-shaped red blood cells block blood flow through tiny blood vessels, causing pain in your chest, abdomen, joints, and bones. The pain can vary in intensity and frequency, and sometimes you might need to go to the hospital.
  • Swelling of hands and feet. When sickle-shaped red blood cells block blood flow to the hands and feet, this causes swelling.
  • Frequent infections. Sickle cells sometimes damage your tissues, leading to ulcers. If they damage your spleen, you could get infections. Doctors sometimes give SCD patients vaccinations and antibiotics to prevent dangerous infections.
  • Yellowing of skin and eyes. This can result from damaged sickle RBCs.
  • Vision problems. Sickle cells can get stuck in the blood vessels that supply your eyes, causing damage to your retina as well as vision problems.
  • Developmental delays. Children with SCD may grow at a slower rate than other children. Teenagers may reach puberty later than their friends.

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Sickle Cell Disease Causes and Risk Factors

Sickle cell disease is caused by a problem in the hemoglobin-beta gene found on chromosome 11. The defect forms abnormal hemoglobin.

Both your parents need to pass the abnormal hemoglobin gene on to you in order for you to develop the disease. If both your parents carry the defective gene, you have a 1 in 4 chance of inheriting the disease and becoming sick with it.

If a child is born with one defective hemoglobin-beta gene, they may become a carrier of the disease. Carriers usually don’t develop SCD symptoms. But they can pass the disease on to their children if their partner also carries the sickle cell trait.

People of some ethnicities are more at risk for sickle cell disease than others.

In the United States, SCD affects African American people more than other races. One in 13 African American babies are born with sickle cell trait, and 1 in 365 Black children are born with sickle cell disease.

SCD also affects people from Hispanic, southern European, Middle Eastern, and Asian Indian backgrounds.

Types of Sickle Cell Disease

There are several forms of sickle cell disease. The type you or your child inherits depends on many things, including the specific type of abnormal hemoglobin you have.

Hemoglobin SS, also called sickle cell anemia, is usually the most severe type of this disorder.

Other common forms include:

  • Hemoglobin SC (usually mild)
  • Hemoglobin sickle beta thalassemia

Rare types are:

  • Hemoglobin SD
  • Hemoglobin SE
  • Hemoglobin SO

Sickle Cell Disease Diagnosis

A blood test can check for the defective form of hemoglobin found in people with sickle cell disease. This test is available for newborns, older children, and adults. In the U.S., this test is a routine part of screening for newborn babies.

If you or your child has sickle cell disease, your doctor might suggest doing some extra tests.  The doctor may recommend a special ultrasound to find out your risk for stroke.  They may also refer you and your child to a genetic counselor (since you both carry the gene).

If you or your partner has sickle cell disease or sickle cell trait, a check of amniotic fluid can let you know if your unborn baby may have the disease. Talk to your doctor to find out more.

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Sickle Cell Disease Treatments

Treatment for people with sickle cell disease usually involves:

  • Avoiding pain crises 
  • Relieving symptoms of the disease
  • Preventing complications

Treatments include:

  • Medications 
    • Daily hydroxyurea (Droxia, Hydrea, Siklos) can lower the number of times you have pain crises and might curb other complications like infections and anemia. This medication shouldn’t be taken if you're pregnant.
    • Pain relievers can help when you are having a pain crisis.
    • Other drugs can reduce the frequency of pain crises, such as crizanlizumab (Adakveo) and L-glutamine oral powder (Endari). The latter is given by injection.
    • Voxelotor (Oxbryta) can help with anemia. 
  • Blood transfusions
  • Stem cell transplants might cure the disease for some children and teenagers.
WebMD Medical Reference Reviewed by Hansa D. Bhargava, MD on July 05, 2020

Sources

SOURCES:

National Human Genome Research Institute: “Learning About Sickle Cell Disease.”

National Heart, Lung, and Blood Institute: “Sickle Cell Anemia,” “How is Sickle Cell Disease Diagnosed?”

Mayo Clinic: “Sickle Cell Anemia.”

CDC: “Facts About Sickle Cell Disease.”

National Institutes of Health, Genetics Home Reference: “Sickle Cell Disease, Other Names for This Condition.”

Medline Plus: “Sickle Cell Disease.”

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