Sickle cell anemia (SS) or sickle cell disease is a genetic blood disorder where the human body produces abnormally shaped red blood cells, often in the shape of a sickle (crescent shaped). The sickle shape reduces the flexibility of the red blood cells making it difficult for them to pass through small blood vessels.

Hemoglobin – an iron rich protein and the most important substance of a red blood cell – plays a vital role in helping the red blood cells carry oxygen from the lungs to all the various parts of the human body as well as give blood its red color.  A normally functioning red blood cell, contains hemoglobin A, and is soft and round is able to squeeze through tiny blood vessels.  On the other hand, Hemoglobin S and hemoglobin C are abnormal types of hemoglobin.

People affected with sickle cell anemia produce a different form of hemoglobin A called as hemoglobin S. Red blood cells that contain hemoglobin S have a far reduced life span than normal ones. They become distorted, rigid and have great difficulty passing through small blood vessels. Sickle shaped cells block blood vessels making smooth blood flow difficult to all parts of the body. Tissue damage is a serious effect of sickle cell disease as blood tissues do not receive normal flow of blood (in turn oxygen) causing damage.

Further, this abnormality can result in serious complications such as serious infections, chronic anemia and organ failure. Sickle cell anemia can often result in reduced life expectancy (on an average 42 years for men and 48 years for women).

As this disease is inherited, the people having sickle cell anemia tend to inherit two copies of sickle cell genes; one from each parent and these two copies of sickle cell gene triggers the body to produce abnormal hemoglobin.

Types of Sickle cell disease

Sickle-cell anemia is also referred to as ‘HbSS’, ‘SS disease ‘or ‘hemoglobin S’. Some other rare forms of sickle-cell disease include sickle hemoglobin disease (HbSC), sickle beta zero thalassemia (HbS/β⁰) and sickle beta plus thalassemia (HbS/β⁺). These sickle cell diseases are compound heterozygous states. Persons suffering from these rare types of sickle cell anemia have only one copy of the mutation gene that causes the disease (Hbs) and one copy of another abnormal hemoglobin allele.

Generally, people with sickle cell anemia make a different form of hemoglobin A which is called as hemoglobin S (sickle). Red blood cells containing haemoglobin S do not live longer as compared to haemoglobin A. Hemoglobin S is associated with several types of sickle cell disease. Some of the most common are:

• Sickle Beta Plus Thalassemia (HbS/β⁺)

Sickle Beta plus thalassemia (sickle B+ thalassemia) is inherited and is a lifelong disorder. People affected by this type of sickle cell disease have red blood cells that contain abnormal hemoglobin called hemoglobin S and small amount of the normal hemoglobin called hemoglobin A. In this case, the red blood cells are somewhat small, pale and misshapen.  People with this sickle cell disease are at risk of being infected by pneumonia and may also feel fatigue, weakness or tiredness.  Sickle Beta plus thalassemia cells block small blood vessels in the bones and other parts of the body which usually causes pain in the arms, legs, back and stomach.

• Sickle  Hemoglobin C disease (SC)

Sickle hemoglobin C disease is a disorder which is inherited and it is present at birth that affects the shape and function of the red blood cell. This disorder causes the red blood cells to change from a soft, round shape to a hard, crescent or ‘sickle’ shape when they give off oxygen due to abnormal haemoglobin. The most common symptoms of this disease are mild anemia followed by infection and pain.

• Sickle Beta Zero Thalassemia (HbS/β⁰)

People suffering from Sickle Beta Zero Thalassemia are at an increased risk of serious infections such as meningitis (infection of the brain), pneumonia, septicemia (blood poisoning) and osteomyelitis (infection of the bone). This disease is similar to sickle cell anemia which causes the cell to become small, pale and misshapen. It is generally inherited and is a lifelong disorder.

Sickle cell anemia causes

The person suffering from sickle cell anemia tends to inherit two copies of sickle cell genes, one from each parent and these two copies of sickle cell gene triggers the body to produce abnormal Haemoglobin also known as hemoglobin (S).

Sickle cell anemia is caused by a mutation in the gene which helps the body to make haemoglobin. This disease is inherited right from birth as parents pass on the defective form of gene to the child. People with sickle cell trait have one normal haemoglobin gene and one defective form of gene.

Parents with an autosomal recessive disorder do not themselves show signs of the disorder. Instead, they have one normal hemoglobin gene which makes healthy  hemoglobinA and one abnormal hemoglobin gene which makes unhealthy hemoglobin S.  They tend to have more normal hemoglobin than abnormal hemoglobin thus preventing them from getting sickle cell anemia.

Sickle cell trait

Sickle Cell trait (AS) is not a sickle cell disease. It is an inherited condition in which the body produces both hemoglobin A and S in the red blood cells, but where hemoglobin A is produced in more quantities than hemoglobin S. In heterozygous people, who have only one sickle gene and one normal adult hemoglobin gene, it is referred to as ‘HbAS’. People who have sickle cell trait inherit only one copy of the sickle cell gene from one parent and do not suffer from sickle cell anemia.

Generally people who have sickle cell trait are healthy. As people with sickle cell trait tend to have more normal hemoglobin (A) than abnormal hemoglobin(S), it prevents them getting sickle cell anemia.

• How is sickle cell trait inherited?

Humans inherit a lot of their traits from their parents – from blood type, hair and eye color to a lot of other physical traits. Much in the same way, sickle cell conditions are inherited, where the types of hemoglobin a person produces in the red blood cells depend upon what hemoglobin genes the person inherits from the parents. Similar to most genes, hemoglobin genes are also inherited in two sets, one from each parent.  The possibilities of a person being affected by sickle cell anemia depend on the genes inherited from their parents.

• If one parent has sickle cell anemia and the other is normal, all children can still have sickle cell trait.
• If one parent has sickle cell anemia and the other has sickle cell trait, then there is a 50% chance of the child having either sickle cell disease or sickle cell trait.
• When both parents have sickle cell trait, there is a 25% chance (1 of 4) of the child having sickle cell disease.

Sickle cell anemia symptoms

There are several signs and symptoms indicating sickle cell anemia. The severity of symptoms varies from patient to patient. The most common symptoms include:

• vomiting
• panic attack
• bone pain
• joint pain
• abdominal pain
• paleness
• blood in urine

The severity of sickle cell anemia varies from people to people.  For some the condition could be mild and may not show any signs or symptoms of the disease but in some cases the condition could be severe where the person might need to be hospitalized immediately. In severe cases sickle cell anemia may also lead to:

• paralysis
• sudden vision problems
• jaundice
• delayed growth and development
• trouble in walking and talking

People living in areas with low oxygen, especially in high altitude regions, may be at a higher risk of suffering from sickle cell disease. Studies have shown that sickle cell anemia is prevalent more in tropical and sub-tropical regions where malaria is a common disease. Some experts believe that a large population from the sub-Saharan regions in Africa may carry the sickle cell anemia gene.  

How can sickle cell anemia be overcome?

As sickle cell anemia is inherited, medical experts are still grappling with finding a sure shot cure to overcome sickle cell disease. But a lot of preventive measures can be adopted to keep sickle cell disease at bay. For maintaining good health diagnosis of sickle cell disease very early is essential. Some medication can include penicillin prophylaxis, vaccination against pneumococcus bacteria and folic acid supplementation.

Well-balanced dietary intake is necessary to maintain the general well-being of patients suffering from sickle cell anemia. It is also important that the patients receive all available immunizing agents. Nutritionaldeficiencies should be corrected when present, folate supplementation is especially important to develop resistance against various infections and also helps to prevent anemia.

To deal with sickle cell anemia one should take rest, avoid alcohol, avoid physical and emotional stress, avoid sources of bacterial, viral and fungal infection.

Eating foods rich in folic acid such as beans and leafy green vegetables can also help prevent sickle cell anemia. It is recommended that people suffering from sickle cell anemia should also increase the fluid intake to one and a half to two times the usual amount. The additional fluids increase the fluid volume and encourage mobilization of the abnormal red cells.

As there is no definite cure for sickle cell disease, taking preventive measures would assist in dealing with the sickle cell crises.