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Erin - Sickle Cell Disease

Page history last edited by Erin P 6 years, 9 months ago

 

Sickle Cell Disease

 

Overview

Sickle cell disease affects your red blood cells. It is a very serious disease. Sickle cell disease affects hemoglobin, which is the molecule in red blood cells that carries oxygen to cells in the body. People with sickle cell disease have sickled red blood cells which are half moon shaped cells. Normal red blood cells are round and flexible. Sickled red blood cells breakdown faster than normal blood cells which lowers the number of red blood cells in the body and reduces the flow of oxygen to the cells. This causes a variety of symptoms. A simple blood test can detect Sickle Cell Disease. Sickle cell anemia is the most severe form of the disease. There is no widely available cure for Sickle Cell Disease. Bone marrow transplants have been known to cure Sickle Cell Disease.

 

History

Sickle Cell Disease is a hereditary genetic disease.  Mutations in the HBB gene causes sickle cell disease. The HBB gene provides instructions on how to make the four proteins in hemoglobin. When the gene mutates, it produces a protein in hemoglobin called hemoglobin S. Hemoglobin S causes the distortion in the shape of the red blood cells. The sickled red blood cells are half moon shaped and inflexible.  They can get stuck in small blood vessels and cause serious health issues.  

 

The first documented and recorded case of Sickle Cell Disease was in 1910. Walter Clement Noel was born on the north side of Grenada, a small Caribbean island. In 1904, he travelled to New York on his way to study medicine in Chicago. When he arrived, he had a leg ulcer, which was later determined to be from sickle cell disease. In November 1904, he started to have respiratory issues and sought medical treatment. The doctor noted that his blood contained pear-shaped and elongated red blood cells. Over the next 2 and a half years, Walter dealt with many health problems such as bronchitis. He was hospilitized with "a bilious and muscular attack" and had knee pains. These were all symptoms of the disease. In 1949, Sickle Cell Disease became the first reported molecular disease. Walter became the first person described with Sickle Cell Disease.  In 1977, the gene responsible for Sickle Cell Disease was mapped. 

 

Symptoms

People with Sickle Cell Disease start to have symptoms in their first year of life. The effect of Sickle Cell Disease is that it prevents oxygen from traveling into your spleen, liver, kidneys, lungs and heart. Your spleen is the most common organ to be destroyed and if it is infected you will experience infections a lot. Any organ you have with little to no oxygen traveling into it will start to die. The sickled red blood cells don't live as long as the normal ones. And if the sickled cells get caught in your capillaries it can cause a serious amount of pain called crises. Some symptoms of sickle cell disease are delayed growth, strokes, skin ulcers, gallstones, high blood pressure and jaundice, which is a yellowing hue to the skin and eye from related liver problems. Common health problems from Sickle Cell Disease are anemia, infections, pain episodes, blindness, strokes, acute chest syndrome and hand-foot syndrome. If you have sickle cell disease, you are only likely to live for 30 years.

 


 

 

Treatment

Bone marrow transplantation is the more common approach to cure Sickle Cell Disease. A patient would need to have a healthy, genetically compatible sibling donor. The patient would be implanted with their sibling's healthy cells. The issue is that it is very risky and only about 18% of people have healthy matched sibling donors. Another treatment is Gene Therapy. In 2001 Harvard Medical School and MIT cured Sickle Cell Disease in mice. 

 

Because bone marrow transplants are risky and matches are hard to find, treatment is designed to relieve pain and prevent complications. Treatment could include blood transfusions, pain medicine, oxygen and antibiotics. People with Sickle Cell Disease should drink plenty of fluids and avoid physical exertion.

 

Side Effects to Bone Marrow Transplantation

Possible side effects include infections, low platelets and low red blood cells, pain, fluid overload, respiratory distress, organ damage, loss of a transplanted organ or tissue, or the donated marrow causes an immune reaction against the patients body. 

 

Untreated Sickle Cell Disease

If Sickle Cell Disease is left untreated, children could develop slower, less oxygen will travel to their organs, cells and tissue. As a result, the child would become really light, having a low weight, and delayed puberty would often result. 

 

How to get the Disease

Sickle Cell Disease is an inherited disease and it's an autosomal recessive pattern. In order to have Sickle Cell Disease, you must have inherited two copies of haemoglobin S from your parents (one from each parent). Sickle cell disease is present at birth and newborn babies are tested for it right away. Sickle Cell Disease has affected millions of people worldwide and still does. The gene is more commonly found if you have ancestors from Africa, Greece, Turkey, Italy, India, Central America and parts of the Caribbean. It is most commonly affects African Americans and Hispanic Americans in the United States. It is possible to be a carrier of Sickle Cell Disease and have no symptoms.  This is known as the Sickle Cell Trait.  This happens when only one parent passes on the sickle cell gene to a child. The child will have one normal hemoglobin gene and one defective form of the gene.  The child may have some sickle cells but doesn't experience any symptoms. The child is considered a carrier of the disease and can pass it onto to his children.

 

 

Controversies

The US National Collegiate Athletic Association (NCAA) in 2010 stated that all athletes coming to study and play sports will be tested for Sickle Cell Disease. They put this in place because they were sued when a 19 year old died after an intense football practice and later was found to have Sickle Cell Disease. Those against the NCAA say it violates a person's privacy, causes stigmatization and could prevent the athlete from participating in competitive sports. The issue is that if the person tests positive for Sickle Cell Disease, they could be denied the opportunity to participate in sports and it could categorize them as a carrier of Sickle Cell Disease.  This could viewed as being very discriminating. Athletes of African descent are more likely to have it or be a carrier, which could mean less black athletes allowed to participate in university sports. While the NCAA ha stated that the athletes who test positive will still be allowed to play, they will be closely monitored.  However, their genetic history will not remain private and could cause discrimination and hurt their chances for pro careers.

 

 

Genetic Disorder

A genetic disorder is a disease caused by abnormalities in a person’s genetic material.  There are four different types of genetic disorders. A change or mutation in a single gene is a single-gene genetic disorder.  When this happens, the mutated gene causes the protein to not function properly. There are over 6,000 single-gene disorders, which include sickle cell anemia, Huntington’s disease and Marfan syndrome. A multifactorial genetic disorder involves a mutation of multiple genes in combination with environmental factors. Examples of multifactorial genetic disorders are Alzheimers disease, diabetes and arthritis.  Chromosomal genetic disorders occur when there are abnormalities in the chromosome structure. Chromosomes carry genetic material and missing or extra chromosomes can result in disease. An example of a chromosomal genetic disorder is Down syndrome. Mitochondrial genetic disorders occur when there is a mutation in nonchromosomal DNA of mitochondria.  Mitochondria are found in cells and convert energy from foods into something the cells can use. Examples of mitochondrial genetic disorders include maternally inherited diabetes and deafness and myoclonic epilepsy.

 

Gene Therapy

Sickle cell disease is caused by one defective gene and could be helped by gene therapy. Gene therapy uses the patient's cells instead of drugs or surgery to cure a disease. There are different methods of Gene Therapy: one way is to replace the mutated cell with a healthier copy of it, or just take out the mutated cell, or adding a new cell to fight off the mutated cells. This procedure is still risky and still under examination. Scientists continue to experiment with gene therapy for sickle cell disease but it is a long way till a cure can be found. 

 

 

 

Bibliography

 

 

 

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