What is sickle cell disease (SCD)?

Sickle cell disease is an inherited disorder that affects your red blood cells, producing a negative impact on your health. In SCD, your hemoglobin is not normal and cannot pass easily through your blood vessels. Hemoglobin is a protein that is part of your red blood cells. It is the substance that carries oxygen in the blood.

Normal red blood cells are round and can move through small blood vessels in the body to deliver oxygen. In SCD, a chemical change in hemoglobin causes the formation of long rods. These rigid rods change the shape of the red blood cell into a sickle (which looks like a crescent). The sickle-shaped cells do not pass easily through blood vessels. They can clog or break apart which also leads to decreased red blood cell life. Sickle cells do not live as long as normal red blood cells. This will lead to increased iron storage in the liver and the heart, which could potentially cause damage to these organs. The damage could result in conditions such as liver failure, cardiac arrhythmia (irregular heart rhythms), an enlarged heart (cardiomyopathy) and heart failure.

How common is sickle cell disease (SCD)?

SCD results from sickle cell trait (SCT). Sickle cell trait happens when people have one sickle cell gene and one normal gene. If you just have the SCT, you usually do not have symptoms and you don’t have SCD. However, you can pass SCT to your children. If both parents have the trait, the child may be more likely to have some type of sickle cell disease.

While there are an estimated 1 million to 3 million people in the U.S. who have SCT, there are only about 100,000 people with SCD.

Who is affected by sickle cell disease (SCD)?

Sickle cell trait, and therefore SCD, is found more often in certain ethnic groups, including African Americans, Hispanics, South Asians, Southern European Caucasians, and Middle Easterners. In the United States, about 1 in 350-400 African American babies have sickle cell disease. Worldwide, it is estimated that there are 300 million people with sickle cell trait. About one-third of this number are in sub-Saharan Africa.

What are some common types of sickle cell disease?

Sickle cell disease is a group of disorders that affect the hemoglobin including:

  • Hemoglobin SS (HbSS) disease.
  • Hemoglobin SB+ (beta) thalassemia.
  • Hemoglobin SB0 (beta-zero) thalassemia.
  • Hemoglobin SC disease.
  • Hemoglobin SD disease.
  • Hemoglobin SE disease.
  • Hemoglobin SO disease.

What causes sickle cell disease (SCD)?

SCD is an inherited condition. It is caused by defective HBB gene. It is inherited in an autosomal recessive pattern, in which parents of an individual with SCD each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

What are the symptoms of sickle cell disease (SCD)?

SCD signs and symptoms begin to show when a child is around four to five months old. Before that, fetal hemoglobin stops the red blood cells from changing shape (sickling).

Signs and symptoms of SCD varies from person to person. Some people have mild symptoms, while others are frequently hospitalized for more serious complications

Signs and symptoms of SCD include:

  • Pain.
  • Anemia could present as fatigue and weakness.
  • Swelling and inflammation of the joints.
  • Blood blockage in the spleen or liver.
  • Jaundice (yellowing of skin and eyes).

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