Sickle cell anemia is an inherited form of anaemia — a condition in which there aren't enough healthy red blood cells to carry adequate oxygen throughout your body.
Normally, your red blood cells are flexible and round, moving easily through your blood vessels. In sickle cell anemia, the red blood cells become rigid and sticky and are shaped like sickles or crescent moons. These irregularly shaped cells can get stuck in small blood vessels, which can slow down or block blood flow and oxygen to parts of the body
Sickle cell anemia (sickle cell disease) is a disorder of the blood caused by an inherited abnormal haemoglobin (the oxygen-carrying protein within the red blood cells). The abnormal hemoglobin causes distorted (sickled) red blood cells. The sickled red blood cells are fragile and prone to rupture. When the number of red blood cells decreases from rupture (hemolysis), anemia is the result. This condition is referred to as sickle cell anemia. The irregular sickled cells can also block blood vessels causing tissue and organ damage and pain.
Sickle cell anemia is one of the most common inherited blood anemias. The disease primarily affects Africans and African Americans.
- Sickle cell anemia (SCD) is an inherited disorder of the haemoglobin in the blood.
- Sickle cell anemia requires the inheritance of two sickle cell genes.
- Sickle cell trait, which is the inheritance of one sickle gene, almost never causes problems.
- Virtually all of the major symptoms of sickle cell anemia are the direct result of the abnormally shaped sickled red blood cells blocking the flow of blood.
- The current treatment of sickle cell anemia is directed primarily toward managing the individual features of the illness as they occur.
How is sickle cell anemia inherited?
Sickle cell anemia is inherited as an autosomal (meaning that the gene is not linked to a sex chromosome) recessive condition. This means that the gene can be passed on from a parent carrying it to male and female children. In order for sickle cell anemia to occur, a sickle cell gene must be inherited from both the mother and the father, so that the child has two sickle cell genes.
The inheritance of just one sickle gene is called sickle cell trait or the "carrier" state. Sickle cell trait does not cause sickle cell anemia. Persons with sickle cell trait usually do not have many symptoms of the disease and have hospitalization rates and life expectancies identical to unaffected people. When two carriers of sickle cell trait mate, their offspring have a one in four chance of having sickle cell anemia. (In some parts of Africa, one in five persons is a carrier for sickle cell trait.)
At the time of conception, a person receives one set of genes from the mother (egg) and a corresponding set of genes from the father (sperm). The genes exist on structures inside cells called chromosomes. The combined effects of many genes determine some traits (hair color and height, for instance). Other characteristics are determined by one gene pair. Sickle cell disease is a condition that is determined by a single pair of genes (one from each parent).
What Are The Risk Factors For Sickle Cell Disease?
For a baby to be born with sickle cell anemia, both parents must carry a sickle cell gene.
What Are The Symptoms Seen In Sickle Cell Disease?
Signs and symptoms of sickle cell anemia, which vary from person to person and change over time, include:
- Anemia. Sickle cells break apart easily and die, leaving you without enough red blood cells. Red blood cells usually live for about 120 days before they need to be replaced. But sickle cells usually die in 10 to 20 days, leaving a shortage of red blood cells (anemia).
- Without enough red blood cells, your body can't get the oxygen it needs to feel energized, causing fatigue.
- Episodes of pain. Periodic episodes of pain, called crises, are a major symptom of sickle cell anemia. Pain develops when sickle-shaped red blood cells block blood flow through tiny blood vessels to your chest, abdomen and joints. Pain can also occur in your bones.
- The pain varies in intensity and can last for a few hours to a few weeks. Some people have only a few pain episodes. Others have a dozen or more crises a year. If a crisis is severe enough, you might need to be hospitalized.
- Some adolescents and adults with sickle cell anemia also have chronic pain, which can result from bone and joint damage, ulcers and other causes.
- Painful swelling of hands and feet. The swelling is caused by sickle-shaped red blood cells blocking blood flow to the hands and feet.
- Frequent infections. Sickle cells can damage an organ that fights infection (spleen), leaving you more vulnerable to infections. Doctors commonly give infants and children with sickle cell anemia vaccinations and antibiotics to prevent potentially life-threatening infections, such as pneumonia.
- Delayed growth. Red blood cells provide your body with the oxygen and nutrients you need for growth. A shortage of healthy red blood cells can slow growth in infants and children and delay puberty in teenagers.
- Vision problems. Tiny blood vessels that supply your eyes may become plugged with sickle cells. This can damage the retina — the portion of the eye that processes visual images, leading to vision problems.
When Should You See A Doctor?
Although sickle cell anemia is usually diagnosed in infancy, if you or your child develops any of the following problems, see your doctor right away or seek emergency medical care:
- Unexplained episodes of severe pain, such as pain in the abdomen, chest, bones or joints.
- Swelling in the hands or feet.
- Abdominal swelling, especially if the area is tender to the touch.
- Fever. People with sickle cell anemia have an increased risk of infection, and fever can be the first sign of an infection.
- Pale skin or nail beds.
- Yellow tint to the skin or whites of the eyes.
- Signs or symptoms of stroke. If you notice one-sided paralysis or weakness in the face, arms or legs; confusion; trouble walking or talking; sudden vision problems or unexplained numbness; or a headache, call your local emergency number right away.
What A Are Some Of The Complications Of Sickle Cell Disease?
See a complete list of complications here.
How Can We Prevent Sickle Cell Disease?
If you carry the sickle cell trait, seeing a genetic counselor before trying to conceive can help you understand your risk of having a child with sickle cell anemia. He or she can also explain possible treatments, preventive measures, and reproductive options.