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What Causes Sickle Cell Disease? Genes Hold the Answer
General Wellness

What Causes Sickle Cell Disease? Genes Hold the Answer

By Your Health Staff
Posted: September 14, 2023

From the color of your eyes to the texture of your hair, the traits you inherit from your parents through the genes they pass on help make you who you are. Unfortunately, in some cases, certain inherited genes don’t function correctly. That’s what causes sickle cell disease, an inherited blood disorder that leads to a shortage of red blood cells.

Around 100,000 Americans have sickle cell disease, according to the Centers for Disease Control and Prevention. And Memphis has one of the largest populations of adults with sickle cell disease in the U.S. For people with sickle cell disease, knowing what causes it can boost their understanding of this disorder and empower them to manage its effects.

How Gene Inheritance Causes Sickle Cell Disease

To do their jobs, your organs and tissues rely on hemoglobin, a protein in red blood cells that carries oxygen. These cells are round, an ideal shape for moving through blood vessels to every part of the body. Sickle cell disease changes the hemoglobin, producing abnormally shaped red blood cells — with harmful consequences.

“Unlike healthy red blood cells, red blood cells in someone with sickle cell disease are crescent-shaped, like sickles,” says Tanya Myers, operations manager of the Methodist Comprehensive Sickle Cell Center. “These sickle cells aren’t made to pass through blood vessels easily. Instead, they get hung up, bunch together, and can reduce or block blood flow. Plus, these abnormal cells don’t live long. The body can’t replace them fast enough to keep up with the need.”

What causes sickle cells’ strange shape? People born with sickle cell disease inherit a malfunctioning hemoglobin gene from each parent. These genes cause abnormal hemoglobin, which, in turn, forms sickle cells. Inheriting an abnormal hemoglobin gene from one parent and a normal one from the other leads to sickle cell trait. This condition rarely causes symptoms or complications, but patients can pass the sickle cell gene to their children.

Three Main Types of Sickle Cell Disease

Different gene inheritance patterns give rise to various forms of sickle cell disease.

“Inheriting an abnormal gene called hemoglobin S from each parent causes sickle cell anemia,” Myers says. “This is the most common type of sickle cell disease. It also causes the most symptoms and complications.”

In other forms of sickle cell disease, the hemoglobin S gene pairs with other genes coded for abnormal hemoglobin. For example, people with sickle cell anemia receive the hemoglobin S gene from one parent and the hemoglobin C gene from the other, which produces a less severe form of sickle cell disease. 

Inheriting a hemoglobin S gene from one parent and a beta thalassemia gene from the other causes HbS beta thalassemia sickle cell disease. This form of the disease can be moderate or severe, depending on which of the two types of beta thalassemia a person inherits.


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Watch for Warning Signs

Parents can spot the signs of sickle cell disease in their children if they know what to look for. According to the National Library of Medicine, symptoms usually appear before age one.

“If your baby’s skin has a yellow hue, they may have jaundice, which can be a sign of sickle cell disease,” Myers says. “Pay attention to the condition of their hands and feet. If you notice swelling, sickle cell disease may be responsible.”

With anemia, the body is chronically low on red blood cells, which can cause a variety of symptoms. Babies with anemia may be extra tired or fussy. Older children may complain of headaches, dizziness or shortness of breath. The symptoms of sickle cell disease may change as patients age. That’s why it’s important for teenagers to transition from pediatric to adult care when appropriate so they can continue receiving the help they need to control symptoms and complications.

Putting Blood to the Test to Diagnose Sickle Cell Disease

Early diagnosis is key to sickle cell disease treatment, so testing typically occurs at birth as part of a newborn screening. A physician or nurse will prick the baby’s heel to collect a blood sample. Lab tests of the hemoglobin can show whether the baby has sickle cell disease or carries the sickle cell gene. Blood tests can also reveal whether adults have sickle cell trait and inform their family-planning decisions.

Diagnosis doesn’t always have to wait until birth. Physicians can diagnose sickle cell disease during pregnancy by testing the amniotic fluid or the placenta.

Controlling Complications

Sickle cell disease is curable with a stem cell transplant, but this complex treatment isn’t an option for all patients. For most, the goal of the other treatments is to reduce or alleviate complications of the disease so they can enjoy the best quality of life possible.

Some of the complications of sickle cell disease include:

Acute chest syndrome 

A life-threatening condition, acute chest syndrome occurs when oxygenated blood can’t reach the lungs, causing pneumonia-like symptoms. A medication called hydroxyurea can reduce the risk of acute chest syndrome.


People with sickle cell disease are more vulnerable to the flu and other infections. To protect against germs, wash your hands often and stay up to date with recommended vaccinations, including the flu vaccine

Pain crises

Pain due to blocked blood flow is known as a pain crisis. This discomfort usually affects the chest, back, hands and feet. Hydroxyurea can help manage pain crises, but lifestyle changes play an important role, too. Staying hydrated, avoiding excessively hot or cold temperatures and staying away from high-altitude and low-oxygen environments can reduce the risk of pain crises.


Lack of blood flow to the brain can lead to a stroke. To reduce your risk, follow a heart-healthy lifestyle that includes a nutritious diet and regular exercise. An imaging test called a transcranial Doppler ultrasound can help physicians better understand stroke risk in children with sickle cell disease. 

“The key to living well with sickle cell disease is to follow your physician’s treatment plan,” Myers says. “Your plan may include medications and lifestyle changes to maximize your ability to manage the disease. Your journey with sickle cell disease is unique — and your treatment plan will be tailored to you.”

Don’t Let Sickle Cell Disease Control Your Life 

The specialists at the Methodist Comprehensive Sickle Cell Center can help you. For more information or to schedule an appointment, call 901-478-2760.

Contact Our Sickle Cell Center Today