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 hemoglobin* S, an abnormal type of hemoglobin. 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.
Hemoglobin – 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 hemoglobin A.
Hemoglobin S and hemoglobin C are abnormal types of hemoglobin.

Normal red blood cells 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.
Sickle cell disease is an inherited blood condition common among people of African ancestry, the Arabian Gulf , South Europe, central and southern India.  It results when abnormal haemoglobin genes are inherited from both parents.

The most common situation is that the parents carry a gene for sickle cell haemoglobin, the sickle cell trait, which is harmless to the carrier and easily detected in the laboratory. If two people with the sickle cell trait have children together, there is a 1 in 4 risk at every pregnancy that the child will inherit the abnormal gene from both parents and have homozygous sickle cell or SS disease.  

In this condition, the sickle haemoglobin results in abnormal red cells causing rapid destruction (anaemia, jaundice, gall stones) but also blocking blood flow in the tissues (bone pain crisis, pneumonia, strokes and many other problems). Other abnormal genes such as HbC or beta thalassaemia, when inherited with HbS may also cause serious symptoms.

Children with the disease encounter life threatening problems in the first year of life, many of which may be prevented or effectively treated as long as the disease has been diagnosed at birth.  Newborn screening and follow-up of affected children has therefore become routine in developed societies. In later life, some serious complications may be prevented by prolonged transfusion, hydroxyurea, or bone marrow transplantation.

These treatments involve complex and expansive technologies and are usually beyond the reach of people in developing societies.  When faced with the scale of this public health problem, approximately 300,000 babies with SS disease are born each year in sub-Saharan Africa, prevention is the most logical way forward. The causal genes are readily detected and populations need to have facilities for screening for these abnormal genes and also counselling and education on their significance. Carriers would then be empowered to select a partner who will give them healthy children.