What is Sickle Cell Disease?
Sickle cell disease is an inherited blood disorder that affects the hemoglobin protein within the red blood cells. Red blood cells are responsible for carrying oxygen throughout the body. Causing abnormal hemoglobin molecules, sickle disease leads to the production of rigid red blood cells with a distorted sickle or crescent shape. As a result, red blood cells break down prematurely and end up clogging the blood flow. Accordingly, sickle cell disease also causes insufficient levels of red blood cells, resulting in the development of anemia.
What causes sickle cell disease?
Sickle cell disease is an inherited condition caused by mutations in the HBB gene, which provides the instructions for the production of two subunits of the hemoglobin protein called beta- globin. The inheritance of sickle cell disease displays an autosomal recessive pattern. The mutated HBB gene from both parents results in sickle cell disease, whereas its inheritance from only one parent combined with a normal gene from the other parent results in a sickle cell trait. Sickle cell disease is categorized into several types depending on the specific mutations and the resulting forms of beta-globin. If a hemoglobin S gene is inherited from both parents, the resulting type of sickle cell disease is called Hemoglobin SS (HbSS) disease which is typically the most severe form of the disease. If a hemoglobin S gene inherited from one parent is combined with a gene coding other types of abnormal hemoglobin such as hemoglobin C, hemoglobin D, hemoglobin E, and hemoglobin O, it results in hemoglobin SC, hemoglobin SD, hemoglobin SE, and hemoglobin SO diseases respectively. Finally, there are Hemoglobin SB+ thalassemia, and Hemoglobin SB0 thalassemia which combine a hemoglobin S gene from one parent with either of the two forms of beta-thalassemia. Similar to hemoglobin SC disease, Hemoglobin SB+ thalassemia causes milder infection, while Hemoglobin SB0 thalassemia causes more severe symptoms.
Is sickle cell disease common?
Sickle cell disease is one of the most common inherited blood disorders worldwide. It affects millions of people around the world. Still, sickle cell disease is more common in people with ancestral links to Africa, Mediterranean countries, India, the Arabian Peninsula, Caribbeans, along with South and Central America. In fact, it is estimated that there are around 300 million people with sickle cell trait and that approximately 1 in 3 of such cases is in sub-Saharan Africa.
What are the Symptoms of Sickle Cell Disease?
Initial symptoms of sickle cell disease often appear during early childhood when a child is a few months old. Although symptoms and severity of sickle cell disease vary significantly among people, common symptoms of sickle cell disease include episodes of pain, anemia, fatigue, shortness of breath, and frequent infections. Common symptoms observed in babies include jaundice, swollen hands or feet, along with anemia-related fatigue and fussiness. Sickle cell disease may also cause spleen damage which could make them more vulnerable against bacterial infections. As it deprives tissues and organs of oxygen, sickle cell disease may cause serious damage to lungs, spleen, kidneys, liver, and brain. As a result, people suffering from sickle cell disease are also at increased risk of developing long-term complications such as pulmonary hypertension, reproductive problems, vision problems, and critical complications such as organ failure, acute chest syndrome, and stroke.
Is there a link between sickle cell disease and malaria?
It was discovered that the altered shape and form of red blood cells of a person with sickle cell disease interfere with the life cycle of plasmodium, which is the parasite that causes malaria by infecting red blood cells. Due to this interference, the immune system eliminates the infected blood cell before the spread of the infection, which results in fewer parasites, milder infection, and easier recovery.
Researchers have suggested that this connection could explain the commonality between the geographical distribution of the two diseases and the preservation of the sickle cell gene within the natural selection process. Several researchers also investigated this connection and confirmed that people with the sickle cell trait had significantly lower levels of parasites in their blood, were less likely to develop severe infections or get hospitalized, and more likely to survive and recover quickly from malaria. Yet, unlike sickle cell trait, sickle cell anemia (HbSS) does not provide protection against malaria. A study of children in Kenya has illustrated that children with sickle cell anemia (HbSS) were the least likely to survive a malaria infection, whereas children with sickle cell trait were the most likely.
How is sickle cell disease treated?
As of now, the only cure treatment that could potentially cure sickle cell disease are bone marrow or stem cell transplants. However, these are highly risky operations and research on treatment strategies for sickle cell disease is ongoing. The current treatment strategies for sickle cell disease focus largely on the prevention of complications and management of symptoms associated with the condition. Such treatments include vaccines and penicillin against infections, blood transfusions against severe anemia, transcranial Doppler ultrasound (TCD) for the early detection of stroke risk, and pain-reducing medicine for the management of pain. There are also some specific treatments such as L-glutamine, Hydroxyurea, Crizanlizumab, and Voxelotor that can be used to relieve symptoms and reduce the risk of complications depending on the symptoms, infection severity, and overall health of the patient.
What are some of the efforts for raising awareness for sickle cell disease?
World Sickle Cell Day is a United Nations-recognized day to encourage sickle cell awareness on a national and international scale. The United Nations General Assembly issued a resolution on December 22, 2008, recognizing sickle cell disease as a public health hazard and “one of the world’s main genetic illnesses.” The resolution calls on members to raise sickle cell awareness on a national and international scale on June 19th of each year.
How is sickle cell disease diagnosed?
Sickle cell disease is most usually detected during routine newborn screenings or pregnancy screenings. However, blood tests both to check for sickle cell disease and sickle cell trait are widely available for everyone. Moreover, through diagnostic tests analyzing small samples of placenta (chorionic villus sampling) and the amniotic fluid (amniocentesis) can be used for screening purposes during pregnancy.
With our RapidFor™ Sickle Cell Rapid Test Kit, the disorder situation for sickle cell can be diagnosed easily and safely. This test kit is designed for in vitro qualitative determining the subtypes of hemoglobin (HbAA, HbSS, HbSC and HbSß) in human whole blood samples.
References
- Kato, G. J., Piel, F. B., Reid, C. D., Gaston, M. H., Ohene-Frempong, K., Krishnamurti, L., Smith, W. R., Panepinto, J. A., Weatherall, D. J., Costa, F. F., & Vichinsky, E. P. (2018). Sickle cell disease. Nature Reviews Disease Primers, 4(1). https://doi.org/10.1038/nrdp.2018.10
