A Molecular Disease Sickle Cell Anemia


Sickle cell anemia is a molecular disease that is commonly found in Africa and in countries with a history of slave trading (Bloom, 1995). People from the Middle East, Asia and Mediterranean countries are also known to carry the sickle cell gene. Being a molecular disease, sickle cell anemia cannot be transmitted from one person to another through contact. Persons suffering from the disease inherit a defective gene from both parents and this is what leads to the development of the disease (Lehninger, Nelson & Cox, 2005). The major complication associated with sickle cell disease is obstruction of vital organs such as lungs and the brain. The effect to these organs causes respiratory failure and other life-threatening conditions (NHLBI, 2002).

Although sickle cell anemia can have devastating repercussions, early diagnosis and proper management can help to contain the disease. It is therefore important to have those affected by the disease exposed to early treatment.

What is Sickle Cell Anemia?

According to Lehninger, Nelson & Cox (2005), sickle cell anemia is a genetic disease in which an individual inherits a defective form of gene from both parents that leads to the production of impaired hemoglobin. Individuals with this condition are referred to as homozygous. Heterozygous individuals suffer a less severe condition known as sickle cell trait (Lehninger, Nelson & Cox, 2005). The hemoglobin in the body is responsible for transporting oxygen to various parts of the body (Koolman & Roehm, 2005). Patients suffering from sickle cell anemia usually have a low hemoglobin level in the blood. This shape of the cells is caused by tubular filaments formed by the polymerization of sickle cell hemoglobin that renders the hemoglobin insoluble upon de-oxygenation (Lehninger, Nelson & Cox, 2005). This severely impairs oxygen transport within the body. The defective gene contains a point mutation and thymine for adenine that causes the incorporation of the amino acid valine instead of glutamate in the hemoglobin (Koolman & Roehm, 2005).

Complications of Sickle Cell Disease

People with sickle cell anemia suffer from complications resulting from physical exertion such as dizziness, fatigue, heart murmurs, shortness of breath and an increased pulse rate. Their blood has about half the level of hemoglobin than is required. A more serious condition is the blockage of capillaries arising from the abnormally shaped cells that cause severe pain and interfere with the functioning of vital body organs (Lehninger, Nelson & Cox, 2005). The capillary blockage that deprives tissues of oxygen leads to the release of chemicals that cause pain. If the oxygen levels are not restored, organ damage will follow (Bloom, 1995).

Surprisingly though, people who are heterozygous for the trait are resistant to certain lethal forms of malaria (Lehninger, Nelson & Cox, 2005) as the parasite causing malaria cannot survive in them.


Being a genetic disorder, a common method for detecting sickle cell anemia is by use of restriction fragment length polymorphisms (Berg, Tymoczoko & Stryer, 2002). The changes that affect the sickle cell gene often make it difficult to identify certain enzymes in the patient’s body and this makes the Deoxyribonucleic Acid (DNA) to appear in different sizes (Lehninger, Nelson & Cox, 2005). When the DNA of healthy and diseased individuals is cleaved, different fragments are produced that are then detected by gel electrophoresis (Koolman & Roehm, 2005).

Treatment and Management

Clinical innovations such as prophylactic penicillin, hydroxyurea therapy and transcranial Doppler screening have benefited children suffering from sickle cell disease and consequently around 95% of them survive to adulthood (Raphael, Kavanagh, Wang, Mueller & Zuckerman, 2011). Hydroxyurea treatment that increases fetal hemoglobin levels has been effective in reducing occurrence of painful sickle cell episodes (NHLBI, 2002). Blood transfusions can also be used to treat debilitating pain, pulmonary hypertension and anemia associated with chronic renal failure. Bone marrow transplants may be considered for patients whose sickle cell disease is severe enough to warrant the risk (NHLBI, 2002).

Research Advances towards Better Treatment of Sickle Cell Disease

Scientists at the National Heart Lungs and Blood Institute (NHLBI) have developed animal models for the disorder to enable them develop a gene therapy cure for sickle cell disease by correction of the defective gene for its insertion into the bone marrow of patients. This will stimulate the production of normal hemoglobin (NHLBI, 2002). Researchers are also working on a way to reduce weakening of the erythrocyte membrane due to the defective hemoglobin. Moreover, they are investigating the ability of nitric oxide to regulate blood pressure by keeping blood vessels dilated and suppressing coagulation in blood vessels as a means to alleviate capillary blockage (NHLBI, 2002).


As far as genetic disorders go, sickle cell disease is among the most devastating as it strikes children at an early age causing a number of severe complications. With extensive scientific research and different stake holders coming together, it is likely that we can deal with the challenges posed by the disease and make it possible for patients to live prolonged lives.

Reference List

Berg, J. M., Tymozcko, J. L. & Stryer, L., 2002. Biochemistry, 5th edn, New York: W. H. Freeman.

Bloom, M., 1995. Understanding Sickle Cell Disease. Mississippi: University Press of Mississippi.

Koolman, J., Roehm, K. H., 2005. Color Atlas of Biochemistry. Stuttgart: Georg Thieme Verlag.

Lehninger, A. L., Nelson, D. L. & Cox, M. M., 2005. Lehninger principles of biochemistry, 4th edn, New York: W. H. Freeman.

National Heart Lung and Blood Institute (NHLBI)., 2002. Sickle Cell Research for Cure and Treatment. US: NIH 02-5214, National Institute of Health, US Department of Health and Human Services. Web.

Raphael, J. L., Kavanagh, P. L., Wang, C. J., Mueller, B. U. & Zuckerman, B., 2011. Translating Scientific Advances to Improved Outcomes for Children with Sickle Cell Disease: A Timely Opportunity’. Pediatric Blood Cancer, 56 (7), 1005-1008. Web.

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