What is Sickle-cell Hb-C disease?

September 23, 2025 •

3 min read

Affecting approximately 1 in every 1,000 Black Americans, Sickle-cell Hb-C disease is a specific inherited blood disorder that results from inheriting a mix of two different abnormal hemoglobin genes. This condition can cause a range of health issues, though typically less severe than sickle cell anemia.

Quick Summary

Sickle-cell Hb-C disease is an inherited blood disorder resulting from one hemoglobin S gene and one hemoglobin C gene, leading to red blood cells that can become misshapen. This condition is a milder form of sickle cell disease, causing mild anemia and potential pain episodes.

Key Points

Genetic Condition: Sickle-cell Hb-C disease is an inherited disorder caused by inheriting one hemoglobin S gene and one hemoglobin C gene.
Milder but Still Serious: It is generally milder than the most common form of sickle cell disease (HbSS) but can still cause significant health complications.
Pain Crises: The misshapen, rigid red blood cells can block small blood vessels, leading to painful episodes called vaso-occlusive crises.
Important Symptoms: Common symptoms include mild anemia, fatigue, an enlarged spleen, and a higher risk of eye problems (retinopathy) compared to HbSS.
Crucial Management Strategies: Management includes preventive care, pain management, staying hydrated, avoiding temperature extremes, and regular medical checkups.
Diagnosis in Infancy: Most cases are diagnosed through routine newborn screening, allowing for early intervention and care.
Treatment Options Evolving: Besides supportive care, treatments like hydroxyurea and gene therapy are providing new possibilities for management and potential cures.

Understanding Sickle-cell Hb-C Disease

Sickle-cell Hb-C disease, also known as hemoglobin SC disease (HbSC), is a genetic blood disorder. It occurs when a person inherits one gene for hemoglobin S (HbS) from one parent and one gene for hemoglobin C (HbC) from the other. Both HbS and HbC are abnormal types of hemoglobin. This combination causes red blood cells to become stiff, sticky, and sometimes sickle-shaped, which can block small blood vessels and lead to pain and potential organ damage.

The Genetic Inheritance Pattern

For Sickle-cell Hb-C disease to be inherited, both parents must carry an abnormal hemoglobin gene. Typically, one parent has the sickle cell trait (carrying one HbS gene and one normal HbA gene), and the other has the hemoglobin C trait (carrying one HbC gene and one normal HbA gene). Each child of such parents has a 25% chance of having HbSC disease. Genetic counseling can help families understand these risks.

Symptoms and Health Complications

HbSC disease is generally considered a milder form of sickle cell disease (HbSS), but its severity varies. Symptoms can include mild to moderate anemia causing fatigue, and pain episodes (vaso-occlusive crises) from blocked blood vessels. Other potential complications include an enlarged spleen, increased risk of infections, eye problems that could lead to vision loss, gallstones, and bone tissue damage (avascular necrosis).

Diagnosis and Testing

Diagnosis usually happens through routine newborn screening in many countries, including the U.S.. A blood sample is tested for hemoglobin disorders. If the screening is abnormal, further tests like hemoglobin electrophoresis and a complete blood count (CBC) are performed to confirm the diagnosis and assess anemia. Genetic testing can also be used. Early diagnosis is important for timely management.

Treatment and Management

Managing HbSC disease involves controlling symptoms and preventing complications. Treatment is individualized and may include preventive antibiotics for young children, pain management, staying hydrated, regular medical checkups, and vaccinations. Medications like hydroxyurea and blood transfusions may be used for specific complications. Advanced treatments like bone marrow transplants and gene therapies are also available for some patients with severe disease. For comprehensive information on modern therapies, refer to the National Heart, Lung, and Blood Institute (NHLBI) on Sickle Cell Disease Treatment.

HbSC vs. Other Sickle Cell Genotypes


Characteristic	Sickle-cell Hb-C Disease (HbSC)	Sickle Cell Anemia (HbSS)	Sickle Cell Trait (HbAS)
Inheritance	Inherits one HbS gene and one HbC gene	Inherits two HbS genes	Inherits one HbS gene and one normal HbA gene
Disease Severity	Generally milder than HbSS, but still clinically significant	Most common and typically most severe form	Usually causes no symptoms; not a disease
Pain Crises	Episodes occur, but often less frequently than in HbSS	Episodes are common and can be severe	Rare; can occur under extreme stress
Complications	Higher risk of eye problems (retinopathy) and avascular necrosis than HbSS	Higher risk of stroke and severe infections	Low risk; complications rare
Anemia	Mild to moderate chronic anemia	Moderate to severe chronic anemia	No anemia under normal conditions

Living with Sickle-cell Hb-C Disease

Managing HbSC also involves lifestyle choices. Key self-care strategies include staying well-hydrated, managing stress, avoiding temperature extremes, engaging in moderate physical activity, and avoiding smoking. These measures help reduce the risk of complications and improve overall well-being.

Conclusion

Sickle-cell Hb-C disease is a lifelong inherited blood disorder requiring ongoing medical care and careful management. Although often milder than sickle cell anemia, it can still cause serious complications. Early diagnosis and adherence to a treatment plan can help individuals with HbSC lead fulfilling lives. Ongoing research offers hope for better treatments and potential cures.

Frequently Asked Questions

A child inherits Sickle-cell Hb-C disease by receiving one gene for abnormal hemoglobin S from one parent and one gene for abnormal hemoglobin C from the other parent.

No, it is a specific type of sickle cell disease but is not the same as sickle cell anemia (HbSS). It is typically a milder form of the disease, though it still requires lifelong medical attention.

Common symptoms include mild to moderate anemia, fatigue, occasional painful crises, an enlarged spleen, and an increased risk of eye-related complications like retinopathy.

Diagnosis is often made in infancy through routine newborn screening tests. Confirmation is done with specialized blood tests, such as hemoglobin electrophoresis.

Treatment focuses on prevention and management of symptoms. It includes prophylactic penicillin for young children, pain management, hydration, regular checkups, and sometimes medication like hydroxyurea or blood transfusions.

Yes, lifestyle management is crucial. Key recommendations include staying well-hydrated, avoiding extreme temperatures, managing stress, and regular, moderate exercise.

With proper medical care and management, individuals with HbSC can live full and active lives. The prognosis is generally better than for HbSS, but ongoing monitoring and proactive care are essential to prevent and manage complications.

In HbSC, red blood cells contain both abnormal hemoglobin S and C. Under certain conditions, these cells can become misshapen and rigid, leading to blockages in small blood vessels and causing pain and tissue damage.