Menu Close

Hemoglobin C Trait

What is hemoglobin C trait?

Hemoglobin C trait is a change (mutation) in a gene that helps make hemoglobin in red blood cells. All red blood cells contain hemoglobin. Hemoglobin is a protein that carries oxygen from the lungs to all parts of the body.

People with normal hemoglobin have only one type, hemoglobin A. People with hemoglobin C trait have hemoglobin A and hemoglobin C in their red blood cells.

A trait is different from a disease

Most people with hemoglobin C trait have no signs or symptoms of illness. The trait normally does not cause any health problems.

People with hemoglobin C trait do not have hemoglobin C disease or hemoglobin SC disease. They cannot develop the conditions later in life. But they can pass the genes for the diseases on to their children.

  • Hemoglobin C disease is an inherited blood disorder that causes a person to have red blood cells that contain mostly hemoglobin C. Too much hemoglobin C can reduce the number and size of red blood cells in your body, causing mild anemia. Hemoglobin C disease is not a form of sickle cell disease and usually does not cause serious health problems.
  • Hemoglobin SC disease is a type of sickle cell disease. People who have hemoglobin SC disease (also called sickle-hemoglobin C disease) have red blood cells that contain both hemoglobin S and hemoglobin C. Under certain conditions, these red blood cells take on a sickle (or banana) shape and become sticky and hard. Sickle cells can clump together and clog blood vessels. This can cause cell damage and pain. Hemoglobin SC disease requires ongoing medical care.

Risk factors for hemoglobin C trait

Hemoglobin C trait is most common among African Americans or people of African ancestry. In the United States, about one 1 in 40 Black or African American babies are born with hemoglobin C trait. Hemoglobin C trait is also more common in people whose ancestors came from Italy, Greece, Latin America, and the Caribbean. But it is possible for a person of any nationality or ancestry to have hemoglobin C trait.

Tests for hemoglobin C trait

A simple blood test can let you know if you have hemoglobin C trait. These tests are often done as part of routine newborn screening. Your doctor may suggest the test if someone in your family has hemoglobin C trait.

How hemoglobin C trait is inherited

Hemoglobin C trait runs in families. Like eye color or hair color, the genes for hemoglobin C trait are inherited, or passed from parents to children.

Parents who have hemoglobin C trait can have a child with hemoglobin C disease or hemoglobin SC disease. Whether a child has the disease depends on genes from both parents. This is why it is important to understand how hemoglobin C trait is passed on and how it can affect the health of your children and grandchildren.

If one parent has hemoglobin C trait and the other parent has normal hemoglobin: With each pregnancy, there is a 50% (1 in 2) chance of having a child with hemoglobin C trait.

If one parent has hemoglobin C trait and the other parent has normal hemoglobin:

With each pregnancy, there is a 50% (1 in 2) chance of having a child with hemoglobin C trait.

These are the possible outcomes with each pregnancy:

  • 50% (1 in 2) chance of having a child with hemoglobin C trait
  • 50% (1 in 2) chance of having a child without hemoglobin C trait
 
If both parents have hemoglobin C trait: With each pregnancy, there is a 25% (1 in 4) chance of having a child with hemoglobin C disease.

If both parents have hemoglobin C trait:

With each pregnancy, there is a 25% (1 in 4) chance of having a child with hemoglobin C disease.

These are the possible outcomes with each pregnancy:

  • 25% (1 in 4) chance of having a child with hemoglobin C disease
  • 50% (1 in 2) chance of having a child with hemoglobin C trait
  • 25% (1 in 4) chance of having a child without trait or disease
 
If one parent has hemoglobin C trait and the other parent has sickle cell trait: With each pregnancy, there is a 25% (1 in 4) chance of having a child with hemoglobin SC disease, also called sickle hemoglobin C disease.

If one parent has hemoglobin C trait and the other parent has sickle cell trait:

With each pregnancy, there is a 25% (1 in 4) chance of having a child with hemoglobin SC disease, also called sickle hemoglobin C disease.

People who have hemoglobin SC disease have red blood cells that contain both hemoglobin S and hemoglobin C. Hemoglobin SC disease is a lifelong illness that can cause serious health problems. People with the disease need medical treatment.

These are the possible outcomes with each pregnancy:

  • 25% (1 in 4) chance of having a child with hemoglobin C trait
  • 25% (1 in 4) chance of having a child with sickle cell trait
  • 25% (1 in 4) chance of having a child with hemoglobin SC disease (sickle cell disease)
  • 25% (1 in 4) chance of having a child without trait or disease
 

To learn more about hemoglobin C trait, talk to your doctor or genetic counselor. Your care team can give more details about your trait status and that of your child.

Key points about hemoglobin C trait

  • Hemoglobin C trait is inherited or passed down from parents to children, like hair or eye color.
  • Hemoglobin C disease is most common in people of African, Italian, Greek, Latin American, or Caribbean descent.
  • People with hemoglobin C trait have both normal hemoglobin A and abnormal hemoglobin C in their red blood cells.
  • Normally, hemoglobin C trait does not cause any health problems.
  • A simple blood test can let you know if you have hemoglobin C trait.
  • Parents who have hemoglobin C trait can have a child with hemoglobin C disease or hemoglobin SC disease.

—
Reviewed: December 2023

Related content

  • Hemoglobin D Trait

    People with hemoglobin D trait have both normal hemoglobin A and abnormal hemoglobin D in red blood cells. Learn about hemoglobin D and how it is inherited.

  • Sickle Cell Disease

    Sickle cell disease is a group of inherited blood disorders that affect the hemoglobin within red blood cells. Learn more about sickle cell disease.

  • Beta Thalassemia Trait

    Beta thalassemia trait, or beta thalassemia minor, is a missing or damaged gene that can be passed down to children. Learn about beta thalassemia trait.