Sickle cell anemia is a serious inherited blood disorder where the red blood cells, which carry oxygen around the body, develop abnormally.

The disorder mainly affects people of African, Caribbean, Middle Eastern, Eastern Mediterranean and Asian origin. 

Normal red blood cells are flexible and disc-shaped, but in sickle cell anemia they can become rigid and shaped like a crescent (or sickle). The sickle-shaped cells contain defective hemoglobin, the iron-rich protein that enables red blood cells to carry oxygen from your lungs to the rest of the body.

The abnormal cells are also unable to move around as easily as normal shaped cells and can block blood vessels, resulting in tissue and organ damage and episodes of severe pain. Such episodes are known as a sickle cell crisis or a vaso-occlusive crisis. They can last from a few minutes to several months, although on average most last five to seven days.

The abnormal blood cells also have a shorter lifespan and aren't replaced as quickly as normal blood cells. This leads to a shortage of red blood cells, known as anemia.


Symptoms of all anemias include lethargy (a lack of energy), tiredness and breathlessness, particularly after exercise.


Sickle cell anemia is caused by a mutation in the gene that instructs the body to produce hemoglobin.

The sickle cell gene is inherited. To get sickle cell anemia the subject has to inherit the defective gene from both parents. If the gene is inherited from one parent, it is known as the sickle cell trait. It is likely that the blood will contain some sickle cells, but the body will be able to produce normal hemoglobin and won't usually experience symptoms. The subject will be a carrier of sickle cell anemia and may pass the abnormal gene on to the children.

If two people with the sickle cell trait have a child, there's a one in four chance that the child will be born with sickle cell anemia.

Risk Factors

The risk of inheriting sickle cell anemia comes down to genetics. For a baby to be born with sickle cell anemia, both parents must carry a sickle cell gene.


Possible complications include:

  • increased vulnerability to infection
  • stroke – where the blood supply to part of the brain is cut off
  • acute chest syndrome, when the lungs suddenly lose their ability to breathe in oxygen (often the result of an infection)
  • pulmonary hypertension, when the blood pressure inside the blood vessels that connect the heart to the lungs becomes dangerously high

However, following improvements in preventative treatment, many complications associated with sickle cell anemia can be avoided.


You can’t prevent sickle cell anemia, because it’s an inherited disease. If a person is born with it, steps should be taken to reduce complications. People who are at high risk of having a child with sickle cell anemia and are planning to have children may want to consider genetic counseling.