Sickle Cell Disease (SCD)

Sickle cell disease (SCD) is a group of inherited blood disorders that affect hemoglobin, the protein in red blood cells responsible for carrying oxygen throughout the body. Normally, red blood cells are round, flexible discs that can easily move through blood vessels. In people with SCD, a genetic mutation causes their red blood cells to become hard, sticky, and C-shaped, like a farm tool called a sickle.

These "sickle cells" cause a number of serious health problems:

Blocked Blood Flow: The sickle-shaped cells are not flexible and can get stuck in small blood vessels, blocking the flow of blood and oxygen to various parts of the body. This can cause sudden, severe episodes of pain called a pain crisis or vaso-occlusive crisi.

Anemia: Sickle cells die much faster than healthy red blood cells, living only about 10 to 20 days instead of the usual 120 days. This leads to a constant shortage of red blood cells, a condition known as anemia, which can cause fatigue, paleness, and shortness of breath.

Organ Damage: The repeated blockages and lack of oxygen can damage vital organs, including the spleen, kidneys, liver, heart, and lungs, over time.

Increased Risk of Infection: The spleen, an organ that helps fight infections, is often damaged by sickle cells, making people with SCD more susceptible to serious bacterial infections.

Inheritance

SCD is a genetic condition inherited from a person's parents. A child is born with SCD only if they inherit a sickle cell gene from both parents.

If a child inherits one sickle cell gene from one parent and a normal gene from the other, they have sickle cell trait (SCT). People with SCT usually don't have symptoms of the disease, but they can pass the gene on to their children.

Types of SCD

There are several types of SCD, with varying levels of severity, depending on the specific genes inherited from each parent. The most common types include:

Hemoglobin SS (HbSS): This is the most severe form of SCD, where a person inherits a hemoglobin "S" gene from both parents. It is commonly referred to as sickle cell anemia.

Hemoglobin SC (HbSC): This is typically a milder form of SCD, where a person inherits a hemoglobin "S" gene from one parent and a gene for a different type of abnormal hemoglobin called "C" from the other.

Hemoglobin S beta thalassemia: This form of SCD occurs when a person inherits a hemoglobin "S" gene and a gene for beta thalassemia, another type of hemoglobin abnormality.

Treatment

While there is no widespread cure for SCD, treatments are available to manage the symptoms, reduce complications, and improve quality of life. These treatments can include pain medication, antibiotics to prevent infections, blood transfusions, and, more recently, gene therapies.