What is sickle cell disease (and how is it treated)?

Sickle cell disease (SCD) is a group of inherited blood disorders that affect the red blood cells, specifically a molecule in these cells called hemoglobin that delivers oxygen to cells throughout the body. According to the Centers for Disease Control and Prevention (CDC), the condition affects millions of people around the world, including an estimated 100,000 people in the United States.

How do you get sickle cell disease?

For a person to have sickle cell disease, both parents must pass the defective form of the hemoglobin gene to their child. If only one parent passes the gene, the child will inherit the sickle cell trait. This means their blood may have some sickle cells, but they don’t normally get ill.

Sickle cell patients have distorted hemoglobin molecules that stretch red blood cells into a sickle, or crescent, shape. These cells are rigid, and their membrane is damaged and easily destroyed. While a normal red blood cell lives in the body’s circulation for 120 days, sickle cells live around 18 or 19 days. Sickle cells block small blood vessels (capillaries), which slows blood flow to different organs and may cause long-term organ damage. 

“Although the primary abnormality lies within the red cell, sickle cell disease becomes a multisystem disease,” says Abdullah Kutlar, MD, adult hematologist and director of the Sickle Cell Center at Augusta University. “The clinical complications affect all organs in the body from head to toe. It’s associated with stroke, affects the eyes, lungs, spleen, and bones.”

Sickle cell disease mostly affects people whose ancestors came from sub-Saharan Africa, Spanish-speaking regions of the Western Hemisphere (South America, the Caribbean, and Central America), India, and some Middle Eastern and Mediterranean countries. Sickle cell disease happens more often in people from parts of the world where malaria is common—either today or in the past. People who carry the sickle cell trait have a better chance of survival against malaria.

Sickle cell disease happens in 1 out of every 365 African American births; around 1 in 13 Black babies in the U.S. is born with the sickle cell trait.

RELATED: 9 questions to ask a doctor if you’re Black, indigenous, or a person of color

Types of sickle cell disease

Sickle cell disease is a broad term that includes many different forms of the condition. These are the most common types of SCD:

• Sickle cell anemia (HbSS): People with this form of SCD inherit one sickle cell gene from each parent. Sickle cell anemia is usually the most serious form of sickle cell disease.
• Sickle hemoglobin C disease (HbSC): With this type of SCD, one sickle cell gene is inherited from one parent, and from the other, a gene for an abnormal hemoglobin called “C.” It’s usually a milder form of SCD.
• Sickle beta thalassemia (HbS beta thalassemia): People who have this form of SCD inherit one sickle cell gene from one parent and one gene for beta thalassemia (a type of anemia) from the other parent. There are two types of beta thalassemia: “0” and “+”. Hbs beta 0-thalassemia is the more severe type of sickle cell disease, while Hbs beta + is milder.

Symptoms of sickle cell disease

People with sickle cell disease usually start to show signs of the condition when they’re young, around 5 months old. Babies younger than this age don’t show symptoms because fetal hemoglobin protects their red blood cells from sickling. As they get older, sickle hemoglobin replaces the fetal type.

Symptoms and complications of SCD are different for each person and can vary from mild to severe. The most common complication of sickle cell disease is severe pain, called pain episodes or pain crises, which can range from mild to severe. It happens when sickle cells travel through small blood vessels, get stuck, and block blood flow. This is called sickle cell crisis and it is the most common cause of hospital admissions among SCD patients. Other complications include:

• Hand-foot syndrome: This swelling in the hands and feet is normally the first symptom of SCD.
• Anemia: A lack of healthy red blood cells to carry oxygen causes severe anemia where people with SCD will feel tired, dizzy or lightheaded, and have difficulty breathing in severe cases.
• Infection: People with SCD, especially young children, are at an increased risk of infection because of damage to the spleen.
• Acute chest syndrome: This condition looks and feels similar to pneumonia with chest pain, cough, trouble breathing, and fever. It can be life-threatening. 
• Splenic sequestration: This life-threatening condition happens when a large number of sickle cells get trapped in the spleen and cause it to enlarge.
• Leg ulcers: Trauma, infection, inflammation, and poor circulation in blood vessels cause ulcers in the lower part of the leg.

How is sickle cell disease diagnosed?

A blood test is the only way to diagnose sickle cell disease or to find out if someone carries the sickle cell gene that they could pass to a child. 

A healthcare provider will draw blood from an arm vein in adults, and a finger or heel in babies and young children. In the U.S., newborns are routinely screened for sickle cell disease. After blood is drawn, a lab then screens the sample for defective hemoglobin.

Many times, people who are found to carry the sickle cell gene are then referred to a genetic counselor who helps patients and their families understand genetic information and how it affects their medical care or managing their condition.

Can sickle cell be cured?

Living with sickle cell disease can be challenging, but it’s still possible to have a full and healthy life. Over the past 20 to 30 years, medical research, care, and education about sickle cell disease have helped to improve the outlook for people with this condition. 

The number of SCD deaths in younger people has dropped significantly over the past several decades, from 9.3% in 1975 to 2.6% by 1989. A more recent study shows the number of deaths in African American children dropping by as much as 68% over a 16-year period. Researchers credit the decrease to a pneumococcal vaccine released in 2000. People with SCD are less protected from serious and deadly diseases like pneumonia.

Even though children with sickle cell disease are living longer, the condition is still linked to a shorter life span in adults. Research shows the average life expectancy is 42 years for women and 38 years for men.

While pediatric care has accelerated with new treatment centers and active practitioners, adult patients still face gaps in the healthcare system. 

“After a person with sickle cell reaches 18 or 19 years old, they have to leave the pediatric space, and unfortunately it’s the point where some people fall off the cliff,” says Barbara Harrison, genetic counselor and director of Community Outreach and Education for Center for Sickle Cell Disease at Howard University Hospital. “There are not enough qualified, knowledgeable hematologists who are trained in sickle cell disease and are familiar with the complications in adults.”

Another challenge: research funding. Sickle cell disease is one of the most common life-threatening genetic diseases in the U.S. Still, it receives significantly less research funding than other genetic disorders like cystic fibrosis, a disparity some blame on systemic racism in healthcare. “The molecular and genetic basis for sickle cell disease was one of the first discovered in human diseases, yet, we’re quite far behind as far as treatments and the strides that have been taken to help cure the condition,” Harrison says.

Right now, a stem cell transplant (also called a bone marrow transplantation) is the only cure for sickle cell disease. During this procedure, doctors infuse healthy cells (stem cells) into the body to replace damaged or diseased bone marrow. The body makes blood cells in bone marrow at the center of the bone. More often, doctors are using blood and bone marrow transplants from healthy donors to cure SCD, but patients need a donor from someone with similar bone marrow. Transplants can also sometimes cause serious side effects and even death, and they’re not widely available outside of the U.S. and Europe.

Another possible cure on the horizon is gene therapy. It involves removing stem cells that form blood and immune cells from the bone marrow or blood and adding a gene that’s flawed in people with sickle cell disease. Doctors then return the cells to the patient, which leads to the body producing anti-sickling hemoglobin. Researchers are still conducting clinical trials, but initial results look promising. 

For now, effective medication is critical. “We need more therapies while we’re working on high-tech, high-resource therapies such as STEM cell transplant and gene therapy,” Dr. Kutlar says.

Sickle cell treatments

The first step to living a longer life with SCD is finding quality medical care from experts in the condition. Then, the medication that’s right for your specific symptoms.

Hydroxyurea

The standard treatment for sickle cell disease is hydroxyurea, a medication that healthcare providers first used to treat cancer. People with SCD take a smaller dose, and it boosts fetal hemoglobin while blocking many complications of the condition—lowering sickle cell crises, trips to the hospital, pneumonia events, and the need for blood transfusions. 

In recent years, pharmaceutical companies have become more interested in developing new treatments for sickle cell disease. This is due, in part, to a lack of therapies, and because sickle cell disease is a model for treating other conditions like inflammation and diseases of the blood vessels.

Endari (L-glutamine oral powder)

Since 2017, the U.S. Food and Drug Administration (FDA) approved a new treatment for sickle cell disease, the first one in decades. Endari (L-glutamine oral powder) is for people with SCD who are 5 years and older. The drug, a powder that is taken orally, works as an antioxidant to ease serious complications linked to the condition. Researchers have found that people who take Endari have fewer sickle cell crises and trips to the hospital, as well as shorter hospital stays. 

Oxbryta (voxelotor)

In 2019, the FDA fast-tracked approval for Oxbryta (voxelotor), the first drug to treat the causes of sickle cell anemia instead of just its symptoms. “With Oxbryta, sickle cells are less likely to bind together and form the sickle shape, which can cause low hemoglobin levels due to red blood cell destruction,” Richard Pazdur, MD, director of the FDA’s Oncology Center of Excellence (OCE) said in a news release announcing the treatment. “This therapy provides a new treatment option for patients with this serious and life-threatening condition.” Oxbryta is for children and adults 12 years and older. 

Adakveo (crizanlizumab-tmca)

The FDA approved another drug in late 2019, Adakveo (crizanlizumab-tmca), which lowers the number of sickle cell crises in adults and children over the age of 16. The medication is an injection, which people with SCD receive in intervals, every two weeks at first and then tapering off to once a month. 

Augusta University’s Sickle Cell Center was part of a nationwide trial for this treatment, and Dr. Kutlar says the reaction from patients was overwhelmingly positive. “After the study finished, a few patients came to us and said, ‘I was feeling so much better when I was getting those infusions. Is there any way you can put me back on this?’ So, in a nutshell, that was a positive experience from the patient perspective.”

People with sickle cell disease also take over-the-counter or prescription medication for chronic pain and may need blood transfusions to treat complications like anemia or infections.

Sickle cell resources

The United States Congress has designated September as National Sickle Cell Awareness Month to help bring awareness to research and treatment of sickle cell disease. To learn more about this condition, visit:

• Sickle Cell Disease Association of America
• Sickle Cell Disease Coalition
• The Foundation for Sickle Cell Disease Research
• Sickle Cell Disease Foundation
• Sickle Cell Society