What is Sickle Cell Disease?

What is Sickle Cell Disease?

Sickle cell disease (SCD) is an inherited red blood cell disorder. Sickle cells are rigid and crescent-shaped instead of flexible and round like healthy red blood cells. The abnormal sickle shape causes them to get stuck in small blood vessels, clogging blood flow and interfering with oxygen delivery.

Sickle cells tend to die early, resulting in a shortage of red blood cells. The disease can cause pain and other health issues, including sickle cell anemia.

Sickle cell disease is the most common inherited blood disorder the United States, affecting around 100,000 people.

Sickle cell anemia vs. sickle cell disease

Different types of inherited sickle cell genes result in abnormal hemoglobin, the protein in red blood cells responsible for transporting oxygen.

  • Sickle cell anemia (HbSS) is a severe form of sickle cell disease (SCD), where chronically low oxygen levels can cause organ damage. This form can be fatal.
  • HbSS or sickle cell anemia occurs when a child has inherited two sickle cell genes—one from the mother and one from the father—that code for hemoglobin “S.”
  • HbSC is a milder form of sickle cell disease, where a child inherits a hemoglobin “S” gene from one parent, and a different abnormal type of hemoglobin called “C” from the other parent.
  • Sickle Cell Trait (SCT) means that a child has inherited the hemoglobin “S” gene from only one parent, and a normal hemoglobin “A” gene from another. It is not a disease. Babies born with SCT typically don’t exhibit any signs or symptoms of sickle cell disease.

Signs & Symptoms of Sickle Cell Disease


Signs of sickle cell disease and symptoms of sickle cell anemia can vary from child to child.

Common symptoms of sickle cell disease include:

  • Anemia. Sickle cells are easily destroyed and tend to die early, resulting in less red blood cells in the body. This can cause fatigue, dizziness, and shortness of breath.
  • Severe, sudden pain (sickle crisis or pain crisis)
  • Fatigue
  • Swelling of the hands and feet
  • Jaundice - A yellowing of the skin or in the white of the eyes may develop when there is a buildup of bilirubin, the yellow pigment that is produced by the breakdown of red blood cells in the liver.
  • Infections
  • Delayed growth or puberty
  • Eye issues

What Causes Sickle Cell Disease?


Sickle cell disease is passed down from your parents and present from birth. When both the mother and father carry the sickle cell genetic trait, there is a one in four chance that their baby will have sickle cell disease.

A person who inherits only one sickle cell gene is typically healthy. But they are considered a “carrier” of the disease and have an increased chance of having a baby with SCD or a sickle cell anemia mutation if they partner with another “carrier.”

Risk Factors of Sickle Cell Disease

Risk Factors

The risk factors for sickle cell disease depend upon your genetics and your family’s ethnic and racial background. Factors that put your baby at an increased risk for SCD include:  

  • Both parents are carriers of the sickle cell gene
  • Family history of sickle cell disease
  • African American, Mediterranean, or Middle Eastern ethnicity



Sickle cell disease may cause mild to serious complications. Children with SCD can start to exhibit signs of the disease in their first year of life, typically around five months old.

Complications of sickle cell disease include:

  • Acute chest syndrome (ACS)- A life-threatening condition that occurs when sickle cells block blood and essential oxygen from reaching the lungs, causing low-oxygen rates, breathing difficulties, and injury
  • Stroke - When sickle cells get stuck in blood vessels and block blood flow to the brain. Stroke symptoms may include seizures, numbness/weakness in the legs and arms, speech difficulties, and loss of consciousness, and may lead to death.
  • Pulmonary hypertension - More common in adults, SCD may cause high blood pressure in the lungs, which may result in extreme fatigue and life-threatening breathing difficulties
  • Splenic sequestration - Sickle cells may become trapped in the spleen. This can lead to an enlarged spleen and pain in the belly on the left side of the body.
  • Organ damage - Sickle cells block blood flow to various parts of the body and prevent vital organs from getting oxygen. Lack of oxygen-rich blood can cause life-threatening damage to the spleen, kidneys, and liver.
  • Vision loss- Over time, blindness can occur if sickle cells block the blood vessels leading to the eyes.
  • Liver issues - Organ damage caused by SCD can lead to liver problems, including gallstones, acute sickle hepatic crisis, and intrahepatic cholestasis.
  • Leg ulcers- Sickle cell anemia may cause poor circulation in the limbs, resulting in painful open sores on the legs.
  • Priapism - When sickle cells block blood vessels in the penis, it can cause painful, long-lasting erections and lead to impotence.
  • Deep vein thrombosis- SCD can increase the chances of a blood clot developing in a lung or a deep vein. This can cause serious health issues or even death.
  • Pregnancy complications- Pregnant women with SCD are at greater risk of having a miscarriage, a premature birth, and/or a baby with a low birth weight. There is also an increased risk of developing blood clots and high blood pressure.



If you are a carrier of the sickle cell trait, consult a genetic counselor before trying to conceive. Your genetic counselor may recommend genetic testing and can help you understand the risks of having a child born with sickle cell anemia. 

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NewYork-Presbyterian’s sickle cell disease program was established in 1983 and remains one of the most experienced sickle cell centers in the world. We provide expert care for children and teens with sickle cell disease. Our world-renowned pediatricians and pediatric specialists will help you understand the symptoms and complications that can accompany SCD and offer innovative treatment options.

NewYork-Presbyterian offers the latest treatments and care for SCD symptoms and complications of sickle cell disease. Contact us for an appointment today.