Sickle cell disease is a group of genetic disorders that affect hemoglobin. Hemoglobin is a molecule in red blood cells that carries oxygen and delivers it to tissues. Sickle cell disease can be life threatening, but the outlook for people with this condition has improved in recent years.
Healthy red blood cells are round cells that carry oxygen around the body. In a person with sickle cell disease, a problem with hemoglobin means that the red blood cells are C-shaped, like a sickle, and sticky. As a result, they can become stuck in the cardiovascular system and are unable to deliver oxygen effectively.
If the body’s cells do not receive enough oxygen, this can lead to a range of problems, including pain episodes, chest-related issues, and stroke. The person will also be more prone to infections, and they may experience more severe symptoms than someone without the disease would do.
Sickle cells also break down more easily than healthy red blood cells, which can result in low levels of red blood cells. Doctors refer to this as anemia.
In this article, we look at why sickle cell disease happens, how it affects the body, and the treatment options.
Causes and types
A person with sickle cell disease may experience episodes of pain.
Sickle cell disease is a genetic condition. A person can only have it if they inherit one or more faulty genes.
If a person has a faulty gene from just one parent, they will have sickle cell trait but not sickle cell disease. If a person inherits a faulty gene from each parent, they will have sickle cell disease.
There are different types of sickle cell disease:
HbSS: A person inherits two sickle cell genes, one from each parent. They will have sickle cell anemia, which is the most severe type of sickle cell disease. Doctors call it HbSS.
HbSC: A person inherits a sickle cell gene from one parent. From the other parent, they inherit a gene that results in another type of abnormal hemoglobin. HbSC is usually less severe than HbSS.
HbS beta-thalassemia: A person inherits a sickle cell gene from one parent and a gene for beta-thalassemia, another type of anemia, from the other.
If a person has only one sickle cell gene, they will not have sickle cell disease, but they can pass that gene on to their children. A person with one faulty gene has sickle cell trait.
Who does it affect?
Sickle cell disease can affect people of any background, but it is more common in some geographical areas and in people from specific backgrounds.
According to the Centers for Disease Control and Prevention (CDC), about 100,000 people in the United States have sickle cell disease. Among black people in the U.S., 1 in 365 are born with the disease, and 1 in 13 are born with the trait. Sickle cell disease affects about 1 in every 16,300 Hispanic Americans.
Sickle cell disease appears to be more likely in areas where malaria is common. Moreover, the CDC note, people with sickle cell disease seem to have a lower risk of some severe types of malaria.
Symptoms and complications
Sickle cell disease is present before birth. A routine blood test at birth will show whether an infant has sickle cell disease, but they will not have any signs of illness. The reason for this is that newborns have fetal hemoglobin, which is typically present until the age of 4–5 months.
After this, the body will start to replace fetal hemoglobin with sickle hemoglobin.
The signs, symptoms, and complications of sickle cell disease can happen at any age, and they will vary among individuals.
They can include:
- pain episodes
- swelling in the hands and feet
- acute chest syndrome
- vision loss
- enlarged spleen
- leg ulcers
- deep vein thrombosis (DVT)
- liver, heart, or kidney damage
- malnutrition in young people
- infertility in males
- priapism, which is a painful and long lasting erection in males
- pulmonary hypertension, which is high blood pressure in the blood vessels that supply the lungs
- heart failure
- bone and joint damage, due to low blood supply
During a pain episode, sickle cells get stuck and prevent blood from flowing to a part of the body. The pain can range from mild to severe, and it can last any length of time. Emergency treatment and hospitalization may be necessary.
The symptoms of acute chest syndrome include chest pain, coughing, fever, and difficulty breathing. It can be life threatening, and the person may need to spend time in the hospital.
A person with an enlarged spleen may suddenly experience weakness, pale lips, rapid breathing and heart rate, thirst, and abdominal pain. A person with these symptoms needs immediate medical attention.
Knowing how to recognize a sign or complication will increase the chances of accessing effective treatment.
In the U.S., healthcare professionals usually screen newborns for sickle cell disease by carrying out a simple blood test at birth. Prenatal tests are also available.
If people with a family history of sickle cell disease plan to have children, they may wish to undergo genetic testing to find out whether their children are likely to inherit the condition.
Sickle cell disease is a lifelong disorder. A combination of medical options and lifestyle choices can help a person maximize their quality of life.
The Food and Drug Administration (FDA) have approved the following drugs to help reduce the risk of complications:
Hydroxyurea (Hydrea): This medication is suitable from the age of 2 years, although it may not be safe to use during pregnancy.
L-glutamine oral powder (Endari): People over the age of 5 years may use this drug.
Voxelotor (Oxbryta): The FDA have approved this medication for people aged 12 years and over.
The CDC advise adults and children to take certain precautions to reduce the risk of infections. These include:
- practicing regular hand washing
- following food safety guidelines
- staying away from reptiles, such as turtles, as they may carry Salmonella
- having vaccinations for flu, pneumococcal disease, and meningococcal disease
A doctor may prescribe penicillin or another antibiotic for children below 5 years of age.
Transfusion and stem cell transplant
People with severe symptoms may need:
A blood transfusion: This procedure may be necessary in cases involving severe anemia, an enlarged spleen, infections, or other complications.
A bone marrow (stem cell) transplant: A transplant from a matched, healthy donor can cure sickle cell disease, but it can be risky. People who are interested should speak to their doctor about the benefits and risks.
During pregnancy, a person with sickle cell disease has a higher risk of:
- pain and other symptoms
- preterm birth
- having a baby with a low weight
However, appropriate medical care can help reduce these risks.
People with sickle cell disease or sickle cell trait should speak to their doctor before becoming pregnant, if possible. The doctor may recommend genetic counseling.
Many people with sickle cell disease can live a full and active life, especially if they can take action to reduce the effects of the disease.
Healthful lifestyle options that may help include:
- finding a suitable healthcare team
- following the recommended treatment plan, including attending regular health checks
- learning as much as possible about sickle cell disease
- drinking 8–10 glasses of water a day
- avoiding getting too hot or too cold
- engaging in physical activity but also getting enough rest
- following a healthful diet, as this can boost overall well-being
According to a 2010 study, smoking increases the risk of pain episodes and acute chest syndrome in adults with sickle cell disease.
The authors suggest that this is because smoking causes less oxygen to reach the blood through the lungs. A person with sickle cell disease is already prone to having low oxygen levels. Smoking may exacerbate this risk, making symptoms more likely.
Both refraining from smoking and avoiding secondhand smoke may help a person manage sickle cell disease.
Sickle cell disease can be fatal, especially in young children. Between 1990 and 1994, about 1% of children with sickle cell anemia — the most severe form — died during the first 3 years of life.
However, advancements in medical science have improved the outlook for people with this condition.
In 2000, for example, doctors introduced the use of a new vaccine that offers protection from invasive pneumococcal disease. As a result, from 1999 to 2002, the mortality rate in black children aged 4 years or under in the U.S. fell by 42%.
For the best outcome, people should:
- follow their treatment plan
- learn all that they can about the disease and how to manage it
- find out about insurance coverage and whether they are eligible for Medicaid assistance
- consider joining an online forum or patient registry, such as the Sickle Cell Disease Association of America, to access useful resources
The Office of Minority Health also provide information about how to obtain help and support for sickle cell disease.
Scientists are investigating new ways of treating sickle cell disease. Some individuals may wish to speak to their doctor about the benefits and risks of joining a clinical trial. A trial is the final stage of testing a drug or technique. It can offer access to new drugs that are not yet widely available.
Click here to learn more about clinical trials for sickle cell disease.