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Biology 103
2001 Third Web Report
On Serendip

Sickle Cell Disease

Rebekah Rosas

Sickle Cell Disease is an illness that affects people all across the globe. This paper will give a description of the sickness through the discussion of the causes, symptoms, and possible cures. Sickle Cell Disease (SCD) is a "group of inherited red blood cell disorders."(1) These disorders can have various afflictions, such as pain, damage and a low blood count--Sickle Cell Anemia.

The overall incidence of SCD is eight out of 100,000 people. However, it is much more widespread in some people. "One out of 600 African Americans and one out of 1,000 to 1, 400 Hispanic Americans" are affected. (2). However, there are other populations who are especially affected, as well. These include, but are not limited to "Arabs, Greeks, Italians, and people from India."(1) As it is plain to see, the disease can affect many different types of people.

Now that we know whom this illness should concern, we must discuss what exactly the disease is. "The genetic defect that causes sickle cell anemia affects hemoglobin." (3). Hemoglobin is a constituent of red blood cells. Its job is to take oxygen to all the cells and tissues in the body. "Red blood cells that contain normal hemoglobin are soft and round. Their soft texture enables them to squeeze through the body's small blood vessels."(3) People with SCD, however, have a type of irregular hemoglobin. "A genetic error makes the hemoglobin molecules stick together in a long, rigid rods after they release oxygen. These rods cause the red blood cells to become hard and sickle-shaped, unable to squeeze through tiny blood vessels. The misshapen cells can get stuck in the small blood vessels, causing a blockage that deprives the body's cells and tissues of blood and oxygen."(3) Thus, the this is where the name of the disease comes from. It also describes the physical process of what happens when you have SCD.

In order to get Sickle Cell Anemia, you must have the Sickle Cell Trait. This is defined as "A person who carries one sickle hemoglobin producing gene inherited from their parents and one normal hemoglobin gene." (3) People who only have one copy of the mutation have the trait. "It is estimated that 1 in 12 African Americans has sickle cell trait." (3) Having the trait will NOT cause SCD. However, having the gene does allow you to pass the mutation on to your children. In fact, "A child conceived by two people with sickle cell trait has one chance in two of also having sickle cell trait, one chance in four of having sickle cell anemia."(3)

Now that the disease is more clearly defined, we must ask, why did this illness come about? This is one of the most interesting facts about Sickle Cell. Since the trait originated in countries that were ravaged by malaria, it could be said that this trait evolved to fight the deadly mosquito-spread disease. "People with sickle trait were more likely to survive malaria outbreaks in Africa than those with normal hemoglobin, it is believed that genetically aberrant hemoglobin evolved as a protection against malaria."(2) It has also been said that, "People with a single copy of a particular genetic mutation [sickle cell trait] have a survival advantage. One copy of the mutation confers a benefit." (3) Its quite interesting to find that original purpose of this gene was to protect people from malaria. Of course, problems occurred in later generations when unknowing gene carriers began to produce children together.

Symptoms of sickle cell are quite varied. They include "family history of sickle cell anemia, fatigue, breathlessness, rapid heart rate, delayed growth and puberty, susceptibility to infections, ulcers on the lower legs, jaundice, attacks of abdominal pain, weakness, joint pain, fever vomiting, hematuria, excessive thirst, excessive penis pain, priapism, chest pain and decreased fertility." (4) However, the worst symptom of sickle cell has to be when a patient goes into 'crisis.' Dr. Duane R. Bonds describes them as "mini heart attacks throughout the entire body." (3) Furthermore, "in sickle cell anemia, the blood flow can be interrupted to any of the major organs, causing severe pain and organ damage at the site of the blood flow blockage." (3) These painful crises harm the lungs, kidneys, liver, bones, and other organs and tissues.

The anemia is caused when the body realizes that the sickle cells are abnormal, and demolishes them at a quicker pace than it can restore them. This causes a shortage of red blood cells-anemia. "Symptoms of anemia include extreme fatigue and susceptibility to infection." (3) It is plain to see that this affliction can be a very painful and dangerous one.

However, there are ways in which people can combat this illness. First of all, everyone should get tested to see if they are a carrier of the gene. "Forty-two states now have newborn screening programs." (3) Once a person knows they have the trait, they can be prepared for the possibility of passing it on to their children. Also, "prenatal diagnosis of sickle cell anemia is possible." (3) However, once a person is diagnosed with SCD, there are many avenues in which one could pursue for treatment. The most popular and easiest treatment of SCD is penicillin. In 1986 there was a study that found "young children with sickle cell anemia who took penicillin twice a day by mouth had much lower rates of S. pneumoniae infections."(3) It is now recommended that infants with SCD start taking penicillin by the "age of 3 months."(3) This treatment has proven to prolong a patients life.

Another important treatment of SCD is using fetal hemoglobin. This is the "hemoglobin that all of us produce before we're born."(3) This type of hemoglobin actually physically blocks the formation of the building blocks that lead to the sickling of the red blood cells. Yet, "several weeks before birth the fetus' bone marrow usually begins to shut down the production of fetal hemoglobin and starts making adult hemoglobin instead." (3) Interestingly enough, "some people continue to produce fetal hemoglobin throughout their lives."(3) However, studies are under way to find a way to trick the body into continuously making fetal hemoglobin through drug therapy.

Another treatment available to SCD patients is hydroxyurea. Hydroxyurea is a drug approved by the FDA to treat some types of cancers. Doctors found that Hydroxyurea increase the production of fetal hemoglobin. However, this treatment also puts people at risk for obtaining leukemia. So it is currently only recommended to "patients over 18 who have had at least three painful crises in the previous year." (3) There are other treatments available to SCD patients, however, these are much more dangerous and occur much less often.

Blood transfusions are one of these daring actions. Blood transfusions give SCD patients a replenished supply of healthy red blood cells. However, these transplants do not occur often because they can be dangerous, and on top of that, it is very difficult to find an exact match. A possible cure of Sickle cell anemia is a bone marrow transplant. This replaces the defective red blood cells with healthy cells from a donor. "But a transplant is not a realistic option for most people with sickle cell anemia...because of a shortage of compatible donors and because of the risks presented by the drug regimen that is required to prepare a patient for a transplant." (3) Finally, scientist are researching the use of gene therapy to cure SCD. They would like to replace the abnormal genes with standard ones, yet there are significant problems with this type of treatment. One of which is the question of ethics. However, gene therapy will not be a realistic option for several years to come.

The issue of Sickle Cell Disease is a very complex and interesting one. Current research has made advances and is currently seeking cures for those afflicted. Although life threatening, individuals with the illness can in fact live healthy and fulfilling lives. Treatments such the ones mentioned make this a possibility. Also, people affected by the disease can help themselves by living a healthy life which includes eating a proper diet, getting adequate exercise, and reducing stress. As people who are not afflicted by the disease we can do something to help. We can donate blood and bone marrow in hopes of being a match to a suffering patient. This disease does not only affect the African American community, as is popular known, it affects us all.

WWW Sources

1)Sickle Cell Anemia

2) Sickle Cell Anemia

3)New Hope for People with Sickle Cell Anemia ,

4)Sickle Cell Anemia,




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