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Sam- Sickle-cell Disease

Page history last edited by Sam C 7 years, 7 months ago

Sickle-Cell Disease

What is it?

The body makes abnormal cresent-shaped blood cells.  Red blood cells contain hemoglobin.  A person that has sickle-cell disease has red blood cells that containk sickle hemoglobin or hemoglobin S.  Sickle blood cells are sticky and stiff.  The sickle blood cells also block the blood vessels to the limbs.  People with sickle-cell disease are more likely to get an infection.  The most common type of sickle-cell disease is sickle-cell anemia.  This is a diagram of normal blood cells and blood cells in a ppersont hat has sickle-cell disease:

Most people's red blood cells die after 120 days, but a person with sickle-cell disease's sickle red blood cells die after about 10-20 days. 

Genetic Disorders

Some genetic disorders are passed down from the parents like all other genes.  Some genetic disorders are mutations of a chromosome.  About 4000 human diseases are caused by a gene being passed down from the parents.  Some genetics disorders are extra copies of a gene.  A single-gene disorder is when there is a mutation in the DNA of one gene.  These genes cannot do their normal functions.  These are inherited.  Multifactorial disorders occur from enironmental factors and mutations in many genes.  Chromosomal disorders are when there are abnormalties such as extra copies of cromosomes or breaking od chromosomes.  Mitochondrial disorders happen when the mitochondria of a cell are mutated by chromosomes.  To have sickle-cell disease the trait has to be inherited from both parents. Someone with only one gene inherited has the sickle-cell trait and does not experience the symptoms of sickle-cell disease

History, Effect on Humans, Symptoms, Treatment, and Side Effects of Treatment for Sickle-Cell Disease

Sickle-cell disease was discovered in 1904 by James B. Herrick, when his intern,  Ernest Edward Irons, found unusual shaped blood cells in a Grenadian student.  The disease was called sickle-cell anemia by Vernon Mason in 1922.  Symptoms of sickle-cell disease were noticed in a newsletter "Southern Journal of Medical Pharacology" in 1846.  An African medical book decribed the symptoms in the 1870s.  There are reports of a Ghanaian family having the symptoms of sickle-cell disease in 1670.  Linius Pauling and his colleagues in 1949 demonstrated that sickle-cell disease was an inherited trait.  Scientists think that the sickle-cell disease trait in the Arabian peninsula, and there have been 4 different mutation events, 3 in Africa, and 1 in Saudi Arabia or India. 

About 1 in 200 000 children born in Canada have sickle-cell disease.  In the United States of America, about 5 million people have sickle-cell disease.  It is estimated that 32 out of 40 African-Canadians carry the sickle-cell disease trait.

Symptoms of sickle-cell disease appear at the age of 4 months.  Symptoms include:

  • Pains (called crises) in the back, long bones, and chest.  These can last from hours to days.
  • Fatigue
  • Paleness
  • Rapid heart rate
  • Shortness of breath
  • Jaundice
  • Stomach pain
  • Poor eyesight/blindness
  • Confusion 
  • Pain in lower legs
  • Bone infection
  • Spleen not working
  • Gall bladder infection
  • Lung infection
  • Delayed growth
  • Arthritis 

There is no widely available cure to sickle-cell disease.  Blood an marrow stream transplants can cure some people that have sicle-cell disease.  Infants that have sickle-cell disease are given antibiotics and vaccines to help prevent infections.  Pains are treated with over-the-counter medications, fluids, and oxygen therapy.  Opitiods may be needed for a lot of pain.  Many people that have sickle-cell disease are treated with hydroxyurea, a medicine that forces the body to make fetal hemoglobin.  Blood transfusions are also used.  gene therapy and stem cells are being researched to see how they can treat sickle-cell disease. 

Many medicines used to treat sickle-cell disease have mild side effects such as stomach cramping, nausea, and diarrhea.  More serious side edffects for some medicines include lethargy, lack of coordination, and diffuculty concentrating. 

Controversies Surrounding Sickle-Cell Disease

The controversy surrounding sickle-cell disease is in sports.  The NCAA (US National College Athletics Association) is making all athletes test for the sickle-cell trait.  This is required after the death of a 19-year-old who died after football training at Rice University, Texas.  10 Division 1 football players died from football training, not knowing they had the sickle-cell disease.  There is controversy surrounding whether or not the athletes carrying the traits should be able to play.  There are more people of African descent carrying the trait, so many are wondering about their future in NCAA sports.

Gene Therapy

There are many types of gene therapy being experimented with.  One way is replacing the affected gene with a healthy copy of the gene.  Another is "knocking out" the gene that is not working properly.  Reverse mutation can make the gene work properly.  The last is adding a new gene to the body to help fight disease.  Gene therapy is just being experimented with at the moment.  Mice have been cured of lung cancer through gene therapy.   Gene therapy has been used to treat sickle-cell disease in mice.  The anti-sickle-cell disease gene was inserted into the mice, and the sickle-cell disease was reversed. 


http://www.nhlbi.nih.gov/health/health-topics/topics/sca/ (picture)












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