Sickle cell anemia, or sickle cell disease (SCD), is the most common form of inherited blood disorder. SCD affects African Americans at much higher rates than people of other ethnicities.
SCD is congenital, meaning it is present at birth, while symptoms vary between individuals depending on the severity of the condition.
Keep reading to learn more about the causes and symptoms of SCD, including treatment options.
SCD is a congenital disease that is caused by inheriting certain genes.
To develop SCD, a newborn must receive two copies of the sickle cell gene or sickle cell trait (SCT) from their parents. People with one sickle cell gene carry SCT, which typically does not cause severe disease.
However, African Americans are at a much higher risk of experiencing SCD. Researchers believe this could be because SCD evolved in human populations living where malaria is common, to help protect against the disease. With this in mind, people with SCT may be less likely to develop severe malaria infections.
Around 50% of the global population live in areas where malaria exists. The condition is common in large regions of Africa. Therefore, SCD and SCT are more common in people whose ancestors lived in the continent.
People whose ancestors are from other regions where malaria was common are also at a higher risk of inheriting SCD or SCT, including people of:
- Mediterranean descent
- Middle Eastern descent
- South and Southeast Asian descent
- Central and South American descent
- Caribbean descent
Between 1991–2000, the total rate of babies born in the United States with sickle cell anemia was:
- 73.1 cases per 1,000 Black births
- 6.9 per 1,000 Hispanic births
- 3.0 cases per 1,000 white births
According to the Centers for Disease Control (CDC), SCD impacts roughly 1,00,000 Americans and 1 out of every 365 Black or African American births. Experts also believe SCT impacts around 1 in 13 Black or African American babies born.
People with SCD have abnormally shaped hemoglobin, the protein in red blood cells that carries oxygen from the lungs to bodily tissues.
SCD affects cells so that they become crescent- or sickle-shaped instead of being rounded, and they become less rigid than those in people without the condition.
In those with SCD, the shape and rigidness of affected hemoglobin make red blood cells less flexible. Without this malleability, these cells are more likely to get stuck in blood vessels, obstructing blood flow.
Obstructed blood flow tends to trigger:
- tissue and organ death, in severe cases, as they become starved for oxygen
SCD symptoms vary between individuals and depend on the severity of the condition. Early signs of SCD and their most common symptoms include:
- jaundice, a yellowing of the whites of the eyes or skin. In people with darker complexions, jaundice may only be apparent in the eyes.
- darkened urine
- painful swelling in the hands and feet
- excessive or unusual exhaustion or fussiness in newborns or babies
- severe anemia in newborns, which can cause reduced appetite, activity levels, or engagement
- frequent painful episodes
- pale appearance
Complications associated with SCD include:
- organ damage
- lower levels of circulating blood oxygen, causing:
- chest pain
- trouble breathing
- delayed growth and puberty
- detached retina, leading to vision loss, seeing flashes of lights or a shadow at the sides or middle field of vision
- coronary heart disease, pulmonary hypertension, or heart damage
- joint problems such as aseptic necrosis, referring to pain and difficulty with movement or loss of function
- kidney problems
- gall stones
- leg ulcers, painful wounds, or sores
- pregnancy issues
- unwanted, prolonged erections — seek emergency medical attention if erections last longer than 4 hours
- stroke or silent stroke
- liver problems
- spleen problems, such as pain and swelling on the left side of the abdomen
- disability, involving:
- chronic pain
- organ damage
- loss of bodily function or movement
Sickle cell disease usually presents in babies at birth. However, many newborns do not experience symptoms until they are 5–6 months old.
Early diagnosis is critical to treat SCD effectively and reduce the risk of complications. Currently, all babies born in the U.S. undergo testing for the condition using a blood sample that healthcare providers take from the heel.
Doctors can also diagnose SCD in embryos by examining amniotic fluid, the liquid surrounding the embryo. They can also test for the condition by examining tissues from the placenta, the organ connecting the umbilical cord to the womb.
Parents can also undergo screening to determine if they carry the gene or trait for SCD, so they know their child’s chances of inheriting the disease.
Currently, a bone and blood marrow transplant is the only cure for SCD.
This procedure involves destroying or removing the stem cells that characterize the condition using radiation or medications followed by transfusions of healthy stem cells. Once in the body, these cells travel to the bone marrow and produce new, healthy red blood cells throughout the blood.
Other treatments that can help manage SCD include:
- Voxelotor: Oral medicine that stops red blood cells from forming the characteristic sickle-shape and sticking together.
- Crizanlizumab-tmca: Helps stop red blood cells from sticking to blood vessel walls. Doctors administer this intravenously.
- Penicillin: An oral antibiotic people take to reduce the risk of infection. Children under 5 years old with SCD often take them continuously.
- Hydroxyurea: Oral medicine that reduces pain and helps prevent SCD complications. However, it is not safe to take this medication during pregnancy.
- Red blood cell transfusions: Involves infusions of healthy red blood cells to increase flexible red blood cells in circulation. Doctors may occasionally administer them to treat severe SCD, before surgery, or routinely to reduce stroke risk.
Researchers are currently working on genetic treatments for SCD. These therapies can work by:
- restoring genes that characterize the condition
- restoring missing genes
- adding genes that improve cellular function
Gene therapies for SCD involve researchers modifying stem cells from blood or bone marrow, then injecting the modified cells into someone’s blood.
Most people with SCD require medical treatment.
However, several healthful lifestyle habits may make it easier to manage the condition, such as:
- quitting smoking
- eating a healthful, balanced diet rich in heart-healthy foods
- limiting or avoiding alcohol consumption
- staying hydrated
- exercising regularly
Some tips may also make it easier to live with SCD, or care for children with the condition, including:
- avoiding extreme heat or cold or abrupt weather or temperature changes
- avoiding traveling in unpressurized aircraft cabins
- talking to coworkers, childcare workers, teachers, coaches, or other people with SCD, so a person knows the warning signs and necessary accommodations
- managing prolonged, painful erections using light exercise, urinating more, and increasing fluids
- learning how to feel the spleen to tell if it is becoming swollen or hard, especially when ill
- talking to a healthcare professional about associated symptoms such as stress, anxiety, or depression
- getting enough sleep
SCD and SCT impact African Americans at disproportionate rates. This is because SCD and SCT are an evolutionary trait that people developed in response to help protect them from malaria. As such, this condition is common in large parts of Africa.
Symptoms often begin within the first few months of life, but respond well to early, effective treatments.
Contact a doctor as soon as possible if the following symptoms occur:
- changes in skin color
- darkened or increased urination
- appetite or activity level changes
- excessive fussiness or restlessness
- unexplained pain
- swelling, especially in the hands, feet, or ankles