In order for your red blood cells (RBC) to carry oxygen to the rest of your body, the hemoglobin protein found in RBC must be soluble. Hemoglobin transports oxygen from the lungs to the rest of the body. Normal hemoglobin (hemoglobin-A) is smooth and round, allowing easily movement through the blood vessels. In people with sickle cell disease, there is a mutation in the hemoglobin-beta gene found on chromosome 11, which results in the production of abnormal hemoglobin molecules (hemoglobin-S). When hemoglobin-S is deoxygenated, interaction with other hemoglobin cells become hydrophobic, which trigger polymerization of deoxygenated hemoglobin-S allowing them to stick together. This creates their long, rod-like shape. These hemoglobin structures cause RBC to become stiff, maintaining their sickle shape. These irregular shaped cells can stick to the walls of the blood vessels, which can slow or block blood flow and oxygen to the rest of the body. It is like trying to spray water and sand through a hose. Some will get through, but eventually the sand will stop the water from escaping.
Some clinical manifestations of sickle cell disease include anemia, periodic pain, frequent infections, delayed growth, and vision problems. Anemia is a lack of healthy RBC in the blood. Sickle cells are fragile due to its shape. They break apart easily and die, leaving your blood with inadequate RBC supply. Because sickle cells die at a faster rate than normal RBC, a person with SCD is left with lasting anemia. This decreases the amount of oxygen in your body, which in turn can cause fatigue and potentially organ failure.
Episodes of pain can occur because sickle cells can block blood flow in tiny vessels in your chest, bones, muscles, and joints. Some people experience this pain for up to a few hours, while others experience it up to weeks. Depending on the severity, some people may need to be hospitalized.
Due to lack of oxygenated blood to the organs, the immune system may also be compromised. Organs such the spleen plays a vital part in your immune system. It helps fight infection. People with SCD are more prone to infections. In addition, vision problems can occur because tiny blood vessels to your eye can be clogged by sickle cells. This blockage can damage the retina, which is the part of your eye that processes images.
Because this is a genetic mutation of the hemoglobin- beta gene, it can be passed on to offspring. It is an autosomal recessive inheritance, which means that both parents must pass on the mutated gene in order for the child to be affected. If only one parent passes on the mutation, then the child will produce both normal and sickle cells. Though they have sickle cells in their blood, they usually do not show any symptoms.
As previously stated, approximately 100,000 Americans have SCD. The number of cases in the world is unknown. However, according to the CDC, SCD occurs in 1 out of every 500 African-American births, 1 out of every 36,000 Hispanic-American births, and 1 in every 12 African-American.
Unfortunately, there is no cure for SCD and because it is a genetic disease, there is no way of preventing it if you have the mutated gene. However, there are some treatments that could subdue the symptoms of SCD. Bone marrow transplant, though very difficult process and procedure, could help for the body to produce healthy RBCs, which can reduce some of the symptoms of SCD. Antibiotics and vaccines are used to help fight infections due to the compromised immune cells. Doctors may begin to administer antibiotics as early as 2 months and continue administering it until they are 5 years old. Pain relieving medications are used when patients are experiencing episodes of pain from the disease.
A new drug being studied is Hydroxyurea. Studies suggest that it could help reduce the frequency of pain and the need for blood transfusions. It seems to work by stimulation the production of fetal hemoglobin, which is found in newborns. It helps prevent the formation of sickle cells. However, this is still being tested.
Interventions can also be taken to help reduce the symptoms and prevent other conditions. Maintaining a healthy diet may reduce the risk of a stroke due to blockage. Exercise could increase circulation, and help reduce pain. Avoiding infectious areas and maintaining cleanliness could help prevent infections among other things.
It is important to understand as much as possible about the disease. Though there is no cure and it cannot be prevented, education can help those with SCD live a sustainable lifestyle. There are many sources that could help those with the disease deal with its ramifications. Studies today are focused on finding a way to alter this mutation, and hopefully prevent this disease.
References
Brousseau, D. C., Scott, J. P., Badaki-Makun, O., Darbari, D. S., Chumpitazi, C. E., Airewele, G. E., Panepinto, J. A. (2015). A multicenter randomized controlled trial of intravenous magnesium for sickle cell pain crisis in children. Blood, 126(14), 1651-1657. doi:10.1182/blood-2015-05-647107
Data & Statistics. (2015, July 08). Retrieved from http://www.cdc.gov/ncbddd/sicklecell/data.html
Epstein, F. H., & Bunn, H. F. (1997). Pathogenesis and Treatment of Sickle Cell Disease. New England Journal of Medicine N Engl J Med, 337(11), 762-769. doi:10.1056/nejm199709113371107
Rees, D. C., FRCP, Williams, T. N., PhD, & Gladwin, M. T., MD. (2010). Sickle-cell Disease. The Lancet, 376(9757), 2018-2031. doi:10.1016/S0140-6736(10)61029-X
Schultz, C. L., Tchume-Johnson, T., Schapira, M. M., Bellamy, S., Smith-Whitley, K., & Ellison, A. (2015). Adherence to prompt fever evaluation in children with sickle cell disease and the health belief model. Pediatric Blood & Cancer Pediatr Blood Cancer, 62(11), 1968-1973. doi:10.1002/pbc.25634
Sickle cell anemia. (2014, June 11). Retrieved from http://www.mayoclinic.org/diseases-conditions/sickle-cell-anemia/basics/prevention/con-20019348
