Hemoglobin SC (HbSC) Disease: A Type of Sickle Cell Disease

Also called: SC-Type of Sickle Cell Disease, Hemoglobin SC (HSC) Disease, Sickle Cell-Hemoglobin C Disease Syndrome, Hemoglobin Sickle C Disease (Hb S/C)

What Is Hemoglobin SC (HbSC) Disease?

Hemoglobin SC disease is a form of sickle cell disease. It causes pain episodes and a type of anemia because red blood cells break down faster than they should. This might sometimes cause tiredness or weakness.

Other problems can happen too, so it’s important to know which symptoms to watch for and when to call the doctor.

What Happens in Sickle Cell Disease?

Normally, red blood cells look like round discs. But in all types of sickle cell disease, including hemoglobin SC disease, red blood cells can be shaped like sickles, or crescent moons, instead. 

The sickle-shaped cells cause problems because they:

• are stiff and sticky and block small blood vessels when they get stuck together. This stops blood from moving as it should, which can lead to pain and organ damage.
• break down faster than normal red blood cells. That leads to too few red blood cells (anemia).

What Causes Hemoglobin SC Disease?

Sickle cell disease and its related conditions run in families (are genetic):

• In HbSC disease: A child is born with 1 sickle cell (hemoglobin S) gene from one parent and 1 hemoglobin C (Hb C) gene from the other parent. The S and C genes tell the body how to make hemoglobin, the protein inside red blood cells that carries oxygen.
• In the most common kind of sickle cell disease: A child has 2 sickle cell (hemoglobin S) genes. This type of sickle cell disease (sometimes called SS sickle cell disease or HbSS) usually causes more symptoms.
• In sickle cell trait: A child has just 1 sickle cell gene.
• In hemoglobin C (Hb C) trait: A child has just 1 hemoglobin C gene.

Most people with hemoglobin C trait or sickle cell trait don't have symptoms but can pass the gene to their children.

What Are the Signs & Symptoms of Hemoglobin SC Disease?

Symptoms of HbSC can vary. While they’re similar to those caused by HbSS, they’re generally not as severe. The most common problems are:

• Anemia. Having fewer red blood cells can make a person feel tired and have less energy.
• Acute pain. The stiff and sticky red blood cells can collect in clumps that clog small blood vessels. So blood can’t flow easily to carry oxygen to the body and a person feels pain where they don’t get enough oxygen. Things like dehydration, being too cold, or being stressed also can trigger pain.

Sickle cell blockages can also damage organs, like the eyes, bones, or kidneys. If a blockage hurts the lungs or the brain, it can be serious. A person needs to get to the hospital right away. 

Other symptoms can include an enlarged spleen and gallstones.

Some health problems that can happen in HbSS, like stroke or serious infection, are less common in HbSC disease. But hemoglobin SC disease causes more eye problems than HbSS, so regular eye checkups are important.

How Is Hemoglobin SC Disease Diagnosed?

All newborn babies in the United States (and in many other countries) have their blood tested for sickle cell disease as part of newborn screening. Other blood tests (such as hemoglobin electrophoresis) can confirm a sickle cell diagnosis.

Doctors can do genetic testing for hemoglobin SC disease before a baby is born if the parents have sickle cell trait or hemoglobin C trait, or if a family member has sickle cell disease.

How Is Hemoglobin SC Disease Treated?

Treatment for HbSC, like all forms of sickle cell disease, may include:

• antibiotics to prevent infections
• medicine to treat pain
• blood transfusions for severe problems
• other medicines that treat sickle cell disease such as crizanlizumab or voxelotor

Children with hemoglobin SC disease should get all recommended vaccines on time. They also should get the pneumococcal polysaccharide vaccine (PPSV23) and meningitis vaccine at 2 years of age and the flu vaccine each year.

How Can Parents Help?

Children with hemoglobin SC disease need regular visits with their sickle cell team. Working with the team, you can help your child feel good and live a healthy life.

Help your child to:

• Drink plenty of liquids.
• Wash their hands well and often to avoid infections.
• Avoid getting too hot or too cold.
• Manage stress.
• Get enough sleep.

Call the doctor right away if your child is sick or has a fever. 

What Else Should I Know?

Because hemoglobin SC disease is a genetic condition, consider speaking to a genetic counselor about testing other family members and to learn how it runs in families. 

You also can find more information and support online at:

• Sickle Cell Disease Association of America
• CDC: Sickle Cell Disease