Some people say Sickle Cell Disease; others say Sickle Cell Anaemia - are they referring to the same thing and does it matter? Let's find out in the article below or watch here.
What is Sickle Cell Disease?
Sickle Cell Disease is a type of inherited blood disorder that affects a part of the blood called haemoglobin.
Haemoglobin is a protein found inside red blood cells which is responsible for the transport of oxygen in our blood.
Globally, Sickle cell disease (SCD) is most common in sub-Saharan Africa, East Mediterranean areas, the Middle East, and India.
Nigeria, as the most populous black nation in the world, has the highest burden of the disease in sub-Saharan Africa.
Understanding the disease will help in its prevention and treatment.
Effect of Haemoglobin in Sickle Cell Disease
In SCD, the haemoglobin is abnormal because the individual has inherited abnormal haemoglobin genes.
This factor changes the red blood cell and causes the disease.
When the red cell has normal Hb, its shape is like a disc which allows the cell to move freely in the blood and easily through the blood vessels to transport oxygen all around the body.
However, with abnormal haemoglobin, the red cell takes on a sickle shape instead, resembling a crescent moon.
The abnormal shape change means the red cells can no longer travel freely through the blood.
They also become sticky, meaning they clump together and can block the blood cells.
When this happens, it prevents the flow of nutrients and oxygen around the body.
In addition to functioning poorly, the sickle red cells do not live long compared to normal.
A typical red cell usually lives for three-four months (90-120 days) in the blood before their natural death and replacement by new red cells.
Sickle red cells, on the other hand, only live for 10-20 days.
Health effects of Sickle Red Cells
These changes to the red blood cells cause significant problems associated with sickle cell disease - blockage of the blood cells leading to painful crises, strokes and organ damage; while early death of red cells causes anaemia and low oxygen levels.
So that summarises very broadly what Sickle Cell Disease is about.
So what does Sickle Cell Anaemia mean?
However, some several variants or subtypes could be associated with SCD.
These happen when the abnormal S gene is inherited with other genotypes such as Haemoglobin C; the Beta-Thalassemia gene or Haemoglobin D.
They could cause varying levels of disease depending on which gene combinations happen like Haemoglobin SC or Haemoglobin SD or Haemoglobin S-beta-Thalassemia.
When two abnormal S genes are inherited in the same individual, Haemoglobin SS, this results in the severe form of the disease and is called the Sickle Cell Anaemia.
Therefore, inheriting one abnormal S gene confers the carrier state - AS genotype - if there are no other abnormal haemoglobin mutations.
The AS genotype is the carrier state; or trait when an individual has inherited one Hb S gene and one Hb A gene.
They generally do not have a severe illness, but rarely could suffer complications from the presence of the abnormal blood gene.
So Sickle Cell Anaemia is the disease caused by having the SS genotype and is a subtype of the Sickle Cell Disease condition which covers a wide range of problems associated with having the abnormal S gene.
Learn about the Haemoglobin C gene and the Hb S-C conditions here.