Sickle Cell Anemia

Sickle Cell Anemia (one of a group of disorders referred to as Sickle Cell Disease)  is an inherited blood disorder in which the body lacks sufficient red blood cells to transport and distribute oxygen to the organs and tissues. Reason being that instead of the red blood cells maintaining a classic round shape, the sickle cells resemble half moons. 

The right are sickle cells, and to the left, healthy cells. Picture Credits: Britannica

These abnormally shaped cells often clog blood vessels, preventing blood flow. Sickle cells are weak, and have significantly shorter lifespans than normal cells; this causes a blood cell shortage throughout (Normal Red blood cells live for approximately 120 days; sickle cells live for 10-20). 

What are the common symptoms of Sickle Cell Anemia?

As the essential element of Cellular Respiration in cells, oxygen is necessary for our bodies to generate energy-to function- and to grow. Sickle Cell Anemia causes oxygen shortages and thus fatigue. Major pain crises are also caused when sickle cells block blood flow to certain areas. These pain crises occur as episodes which can vary with time and intensity. Certain crises persist for hours, while others for weeks. Some patients may have a few crises a year, whereas others may have a dozen. Blockage of blood flow also leads to swelling of the extremities. Shortage of oxygen also hinders growth in children and delays puberty in teenagers. Sickle cell blockage in the vessels connected to the eyes can damage the retina, and thus impair vision. 

Sickle Cell Anemia may also lead to stroke if there are blood blockages in the cerebral artery, responsible for transporting oxygen and nutrients to the brain. The consistent lack of oxygen also causes organ damage.

How is it caused?

Sickle Cell Anemia is caused by a point mutation in the sickle cell allele of the DNA. An adenine nucleotide (the sickle cell allele) replaces a wild type (thymine), which alters the amino acid produced, and thus causes hydrophobic interactions of the proteins of hemoglobin-which enables red blood cells to transport oxygen. Therefore, the sickle cell proteins form chains and bind into a fiber-like structure-which does not occur under normal conditions. These fibers lead to misshapen, weak, sticky, and rigid red blood cells. 

Homozygous Individuals which inherit 2 sickle cell alleles, one from each parent, have sickle cell disease, and can likely have sickle cell anemia. Heterozygous Individuals which inherit only one sickle cell allele and one healthy allele, still have sickling present in the blood, but the sickling is not severe enough to cause Sickle Cell Disease, although they still carry the sickle cell trait and can pass it to offspring. 

What are the outcomes? Is Sickle Cell Anemia Fatal? 

To date, there is no cure for Sickle Cell Anemia. However, patients may take folic supplements (to promote blood cell creation), hydroxyurea (to reduce the stickiness of cells), blood transfusions, and pain relievers during pain crises or headaches. Scientists have proposed Stem Cell transplants, unfortunately this process is expensive, new, and not readily available to the majority of patients. Gene Therapy is also an alluring option, as the deleterious alleles can be extracted and replaced with healthy alleles. However, this option is also fairly new and requires more testing.

Works Referenced:

“Sickle Cell Anemia.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 30 Jan. 2020, http://www.mayoclinic.org/diseases-conditions/sickle-cell-anemia/symptoms-causes/syc-20355876.

“Sickle Cell Disease.” National Heart Lung and Blood Institute, U.S. Department of Health and Human Services, http://www.nhlbi.nih.gov/health-topics/sickle-cell-disease.

“Sickle Cell Disease.” Sickle Cell Disease | Johns Hopkins Medicine, http://www.hopkinsmedicine.org/health/conditions-and-diseases/sickle-cell-disease.

Team, The Healthline Editorial. “Sickle Cell Anemia: Types, Symptoms, and Treatment.” Healthline, Healthline Media, 23 June 2010, http://www.healthline.com/health/sickle-cell-anemia.

Published by N

A high school student who is passionate about life sciences!

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