Sickle Cell and Thalassaemia Ireland (SCTI)

Sickle Cell Disease

What Is Sickle Cell Disease?

Sickle cell disease is an inherited blood disorder that affects red blood cells. People with sickle cell disease have red blood cells that contain mostly haemoglobin S, an abnormal type of haemoglobin. Sometimes these red blood cells become sickle-shaped (crescent shaped) and have difficulty passing through small blood vessels. When sickle-shaped cells block small blood vessels, less blood can reach that part of the body. Tissue that does not receive a normal blood flow eventually becomes damaged. This is what causes the complications of sickle cell disease. There is currently no universal cure for sickle cell disease.

Haemoglobin is the main substance of the red blood cell. It helps red blood cells carry oxygen from the air in our lungs to all parts of the body. Normal red blood cells contain haemoglobin A. Normal red blood cells that contain haemoglobin A are soft and round and can squeeze through tiny blood tubes (vessels). Normally, red blood cells live for about 120 days before new ones replace them.

People with sickle cell conditions make a different form of haemoglobin A called haemoglobin S (S stands for sickle). Red blood cells containing mostly haemoglobin S do not live as long as normal red blood cells (normally about 16 days). They also become stiff, distorted in shape and have difficulty passing through the body’s small blood vessels.
When sickle-shaped cells block small blood vessels, less blood can reach that part of the body. Parts of the body that don’t receive a normal blood flow eventually become damaged. This is what causes the complications of sickle cell disease although some individuals may be eligible for a curative bone marrow transplant.

Inheritance

Sickle cell conditions are inherited from parents in much the same way as blood type, hair colour and texture, eye colour and other physical traits. The types of haemoglobin a person makes in the red blood cells depend upon what haemoglobin genes the person inherits from his or her parents. Like most genes, haemoglobin genes are inherited in two sets, one from each parent.

Example 1

If both parents have Sickle Cell Trait (AS), they have 1 in 4 (25%) chance of having a child with Sickle Cell Disease at every pregnancy.

Types of Sickle Cell Disease

The most common are:

Haemoglobin SS Disease,
Haemoglobin SC Disease
Sickle Beta-Plus Thalassemia
Sickle Beta-Zero Thalassemia.

The majority of individuals with sickle cell disease have haemoglobin S, but some make a different type of abnormal haemoglobin like haemoglobin C, haemoglobin D, or haemoglobin E. Also, some individuals can have sickle cell disease because of co-inheritance of beta thalassemia. It is important to speak to your physician to understand what type you have.

Example 2

If one parent has Sickle Cell Anaemia (SS disease) and the other is Normal, all of the children will have sickle cell trait (AS)

Symptoms of sickle cell disease

People with SCD start to have signs of the disease during the first year of life, usually around 5 months of age. Early symptoms of SCD may include:

Painful swelling of the hands and feet
Fatigue
A yellowish colour of the skin (jaundice) or the whites of the eyes (icterus)

Effects of the disease varies per each individual and can change over time. The signs and symptoms of Sickle Cell relates to many of the disease complications.

Example 3

If one parent has Sickle Cell Anaemia (SS) and the other has Sickle Cell Trait (AS), there is a 50% chance (or 1 out of 2) of having a baby with either sickle cell disease or sickle cell trait with each pregnancy.

Common complications of SCD

“Pain Episode” or “Crisis”:
Sickle cells don’t move easily through small blood vessels and can get stuck and clog blood flow. This causes pain that can start suddenly, be mild to severe, and last for any length of time.

Infection:
People with SCD, especially infants and children, are more likely to experience harmful infections such as flu, meningitis, and hepatitis.

Hand-Foot Syndrome:
Swelling in the hands and feet, often along with a fever, is caused by the sickle cells getting stuck in the blood vessels and blocking the blood from flowing freely through the hands and feet.

Eye Disease:
SCD can affect the blood vessels in the eye and lead to long term damage.

Acute Chest Syndrome (ACS):
Blockage of the flow of blood to the lungs can cause acute chest syndrome. ACS is similar to pneumonia; symptoms include chest pain, coughing, difficulty breathing, and fever. It can be life threatening and should be treated in a hospital.

Stroke: Sickle cells can clog blood flow to the brain and cause a stroke. A stroke can result in lifelong disabilities and learning problems.

Sickle cell disease or Sickle Cell Trait (SCD) diagnosis
A blood test can show if you have SCD or sickle cell trait. All states now test new-borns as part of their screening programs, so treatment can begin early.
If you are thinking of or considering having children, it is important to have the test to find out how likely it is that you carry the genetic trait for the disease and if your children will have SCD.
By taking the test, you are in a better place to make an informed decision.

Treatments for sickle cell disease
The only cure for SCD is bone marrow or stem cell transplantation. Because these transplants are risky and can have serious side effects, they are usually only used in children with severe SCD. For the transplant to work, the bone marrow must be a close match.
Usually, the best donor is a brother or sister.

Treatments to relieve symptoms, complications and prolong life.

Antibiotics to try to prevent infections
Pain reliefs
Hydroxyurea, ADAKVEO, OXBRYTA
Childhood vaccinations to prevent infections
Blood transfusions and Blood Exchanges