Haematology describes the branch of medicine that focuses on the treatment of blood and the diseases that affect it, such as anaemia or Sickle Cell Disease (SCD). This article has a particular focus on Sickle Cell Disease and the recent research and developments around improving the lives of those affected by the disease.
Sickle Cell Disease is an inherited blood disorder that creates haemoglobin deficiency and crescent-shaped blood cells (‘sickle-shaped’). They have a shorter lifespan compared to regular healthy red blood cells and can block blood vessels, which leads to sickle cell anaemia. The symptoms are often painful for SCD carriers and can include problems such as increased risk of infections, swelling of extremities and delayed growth in children, and is more likely to affect people of sub-Saharan African descent.
But why does sickle cell affect these groups of people? The main reason is to do with genetics and natural selection. People with SCD have developed red blood cells which protect the body against various infections, one of these being malaria. Due to sickled cells being crescent-shaped, the surface area of the red blood cells decreases significantly, meaning that there is no space for the malaria parasite to completely overtake the cell, in turn preventing malaria from becoming fatal once inside the body. Malaria is most detected in sub-Saharan African countries where conditions allow for the presence of mosquitoes (the main carriers of the disease), meaning that over time, a survival advantage against malaria is developed, leading to a higher frequency of people carrying the gene that produces sickled red blood cells. An overproduction of sickled red blood cells leads to sickle cell disease, which can, unfortunately, be fatal.
However, as well as SCD, there is Sickle Cell Trait (SCT). This occurs when an individual has both regular red blood cells and sickle-shaped red blood cells, which means that carrying the gene is not fatal for them, but instead only provides immunity to malaria fatality as the amount of normal, healthy red blood cells outweighs the amount of sickle-shaped red blood cells. This is called heterozygote advantage, and it only occurs in people with SCT as opposed to SCD. Carriers of the sickle cell trait do not have any symptoms and lead a relatively regular life, although inv some cases, carriers have been known to experience a greater amount of fatigue after exercise, and surprisingly, less immunity to other infections. They also have a 50% chance of passing on the gene to their children, who may also experience no symptoms (depending on the genetic makeup of their other parent).
A common misconception is that SCD affects people of African descent only – which has since been proven to be false. It can equally affect those of Mediterranean, Hispanic, and Middle Eastern descent as malaria-carrying mosquitoes are also more prevalent there compared to Nordic or Eurocentric countries where the climate is not as accommodating, therefore meaning that over time, the specific mutation has not developed as it simply was not necessary.
But is there a cure? Sickle Cell Disease is unfortunately not a widely researched disease, and so an effective cure is currently not at large. However, Case Western Reserve University researchers in the United States have been working on developing access to easier diagnosis and treatment for those living with the disease. Currently, the only ‘cure’ is a bone marrow transplant with a ‘sibling donor’ who is genetically compatible with the patient. The issue here is that this method is too risky for most adults, and in the case of children, only around 18% have access to a healthy matching donor. The process is also expensive and poses a threat of post surgical infections, which can become fatal. There is still a glimmer of hope, as there is a newly proposed idea of genetic curative therapy to modify a patient’s haematopoietic stem cells (cells which differentiate into blood cells) to create new, healthy red blood cells which can be given back in a bone marrow transplant for those who do not have a matching donor.
With this hopeful breakthrough, the struggle of living with SCD could potentially be minimised and it could help more people to lead long, healthy and happy lives.