Sickle cell anemia is one of a group of inherited blood disorders marked by flawed hemoglobin, the protein molecule in red blood cells that carries oxygen from the lungs to the tissues in the body. It is the most severe form of sickle cell disease.

Red blood cells that contain normal hemoglobin are disc-shaped and flexible, so they move easily through both large and small blood vessels. People with sickle cell anemia inherit a defective hemoglobin S gene that can cause rigid protein strands to form within red blood cells. This causes the cells to become shaped like a sickle, the farming tool with a semicircular blade like a crescent moon, giving both the cells and the disease their name.

These sickle-shaped cells are not flexible and can stick to vessel walls, causing inflammation in the blood vessels and blockages that can stop or slow the flow of blood.

Furthermore, because these sickle-shaped cells cannot change shape easily, they tend to burst apart, and unlike normal blood cells that live about three to four months, sickle cells last only 10 to 20 days.

The body, which is always making new red blood cells to replace the old cells, may have trouble keeping up with how fast the cells are being destroyed. This leads to an overall shortage of red blood cells in the body and, consequently, anemia.

In addition to anemia, the disease can cause other health problems, including infections, stroke, and kidney disease. These health issues can be long term and can reduce life expectancy.

Causes and Risk Factors of Sickle Cell Anemia

To have sickle cell anemia, a person must inherit two sickle hemoglobin genes, one from each parent. People with sickle cell trait (meaning they inherited only one sickle hemoglobin gene) generally don't have symptoms of sickle cell disease, but they can pass the sickle hemoglobin gene on to their children.

Having a family history of sickle cell disease increases your risk for the disease.

Sickle cell anemia is more common in certain groups. In the United States, sickle cell anemia is most prevalent among Black Americans.

Duration of Sickle Cell Anemia

Sickle cell anemia is generally a lifelong condition, and the only cure is a blood or bone marrow transplant (also called a stem cell transplant). According to the CDC, these transplants are limited to children with severe cases of the disease who have experienced minimal organ damage.
Stem cell transplants are riskier in adults. According to Be the Match, a bone marrow registry, adults with severe sickle cell anemia are able to get a bone marrow transplant only if they join a clinical trial.
However, researchers are looking at new ways to help more people who have sickle cell anemia get a transplant, including blood and bone marrow transplant techniques for children and adults who can’t find a matched donor in the family.
Researchers, including those at the NHLBI, are also exploring ways that genetic therapies might lead to new treatments or a cure.

Prevention of Sickle Cell Anemia

There is no known way to prevent sickle cell anemia. However, you can find out if you carry the gene mutation through a simple blood test. If you don’t have sickle cell anemia but people in your family do, you may have inherited one sickle cell gene; this is referred to as sickle cell trait. If you carry the gene, your chances increase for having a child with either the disease or sickle cell trait.

To be born with sickle cell anemia, a child must inherit two sickle cell gene mutations, one from each parent.

If you carry the mutated gene and your partner carries the mutated gene, there is a 1 in 4 chance that your child will have sickle cell anemia.

If one of you carries the trait, there is a 1 in 2 chance that your child will also carry the trait.

Genetic counselors can help you review your family history, navigate your blood test results, and guide you in making informed decisions with regard to family planning.

A few simple steps can help prevent and reduce the number of pain crises:

  • Drinking plenty of water
  • Avoiding getting too hot or cold
  • Avoiding exposure to high altitudes
  • Avoiding places or situations where there might be low oxygen levels, such as mountain climbing or extremely intense exercise

Research and Statistics: How Many People Have Sickle Cell Anemia?

According to the World Health Organization, about 300,000 infants are born with hemoglobin disorders, including sickle cell anemia, each year.According to the CDC, more than 75 percent of the newborns born with the disease are born in sub-Saharan Africa.In the United States, sickle cell disease, including sickle cell anemia, affects approximately 100,000 Americans, per CDC reports.

Related Conditions and Causes of Sickle Cell Anemia

Although it has long been thought that having sickle cell trait was a largely benign condition, according to an article published by StatPearls in September 2020, research suggests that some people with the trait are more likely to suffer from higher rates of chronic kidney disease and exercise-related sudden deaths.

Resources We Love

American Sickle Cell Anemia Association

This organization, founded in 1971, is the oldest sickle cell research, education, and social services organization in the United States. On its website, you can find information for support groups in your area.

American Society of Hematology

The world’s largest professional society concerned with the causes and treatments of blood disorders, including sickle cell anemia, ASH provides news on clinical and research advances on its website.

Be the Match

This organization's website has the latest information about blood or bone marrow transplants, along with information about joining clinical trials related to the disease.

National Organization for Rare Disorders

A great resource for information about sickle cell disease, this group's website links to current clinical trials and offers valuable information for patients and caregivers.

Sickle Cell Disease Association of America

On this site you’ll find information about the organization's peer-to-peer mentoring program, which helps adolescents and young adults as they transition into adult sickle cell health services. It also features a provider network and advocacy and research information.

Sickle Cell Society 

On this site you can read blog posts by people with sickle cell disease, sharing their experiences and challenges that accompany living with the disease.

Editorial Sources and Fact-Checking


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Sickle Cell Disease. MedlinePlus. November 25, 2020.

Hemolytic Anemia. Johns Hopkins Medicine.

Sickle Cell Disease. National Heart, Lung, and Blood Institute. September 1, 2020.

What You Should Know About Sickle Cell Trait. Centers for Disease Control and Prevention.

Sickle Cell Disease: Research for Your Health. Centers for Disease Control and Prevention. September 1, 2020.

Sickle Cell Anemia: Symptoms and Causes. Mayo Clinic. January 30, 2020.

Sickle Cell Disease Emergency Guide. Centers for Disease Control and Prevention. October 21, 2019.

About Sickle Cell Disease. National Human Genome Research Institute. May 26, 2020.

Complications and Treatments of Sickle Cell Disease. Centers for Disease Control and Prevention. June 3, 2020.

Sickle Cell Disease: Outlook/Prognosis. Cleveland Clinic. February 25, 2020.

Reducing the Burden of Sickle Cell Disease. National Heart, Lung, and Blood Institute. August 1, 2011.

Lubeck D, Agodoa I, Bhakta N, et al. Estimated Life Expectancy and Income of Patients With Sickle Cell Disease Compared With Those Without Sickle Cell Disease. JAMA Network Open. November 2019.

Sickle Cell Disease (SCD). Be the Match.

Genetic Therapies. National Heart, Lung, and Blood Institute.

Brandow AM, Carroll CP, Creary S, et al. American Society of Hematology 2020 Guidelines for Sickle Cell Disease: Management of Acute and Chronic Pain. Blood Advances. June 2020.

Mahmood LA, Reece-Stremtan S, Idiokitas R, et al. Acupuncture for Pain Management in Children With Sickle Cell Disease. Complementary Therapies in Medicine. March 2020.

COVID-19 (Coronavirus Disease): People with Certain Medical Conditions. Centers for Disease Control and Prevention. December 1, 2020.

COVID-19 and Sickle Cell Disease: Frequently Asked Questions. American Society of Hematology. September 22, 2020.

Sickle Cell Disease. World Health Organization Regional Office for Africa.

Sickle Cell Disease (SCD): Data and Statistics on Sickle Cell Disease. Centers for Disease Control and Prevention. October 21, 2019.

Sickle Cell Disease. American Society of Hematology.

Ashorobi D, Ramsey A, Yarrarapu SNS, Bhatt R. Sickle Cell Trait. StatPearls. September 16, 2020.


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