Sickle Cell Disease Essay, Research Paper
The sickle cell disease is an inherited blood disorder that affects red blood
cells. People with sickle cell have red blood cells that have mostly
hemoglobin’s, Sometimes these red blood cells become sickle-shaped or crescent
shaped and have trouble going through small blood vessels. When sickle-shaped
cells block small blood vessels, less blood can get to that part of the body.
Tissue that does not get a normal blood flow eventually becomes damaged. This is
what causes the problems of sickle cell disease. As to this day there is really
no cure for sickle cell disease. Red blood cells take oxygen from the air we
breathe into our lungs to all parts of the body. Oxygen is carried in red blood
cells by a substance called hemoglobin (Hemoglobin ? is the main substance of
the red blood cell. It helps red blood cells carry oxygen from the air in our
lungs to all parts of the body). Normal red blood cells contain hemoglobin A.
Hemoglobin S and hemoglobin C are abnormal types of hemoglobin. Oxygen is
carried in red blood cells by a substance called hemoglobin. The main hemoglobin
in normal red blood cells is hemoglobin A. Normal red blood cells are soft and
round and can squeeze through tiny blood tubes (vessels). Normally, red blood
cells live for about 120 days before new ones replace them. People with sickle
cell conditions make a different form of hemoglobin A called hemoglobin S (S
stands for sickle). Red blood cells containing mostly hemoglobin S do not live
as long as normal red blood cells (normally about 16 days). They also become
stiff, distorted in shape and have difficulty passing through the body’s small
blood vessels. When sickle-shaped cells block small blood vessels, less blood
can get to that part of the body. Tissue that does not receive a normal blood
flow eventually becomes damaged. This is what causes the complications of sickle
cell disease. There are several types of sickle cell disease. The most common
are: Sickle Cell Anemia (SS), Sickle-Hemoglobin C Disease (SC) Sickle Beta-Plus
Thalassemia and Sickle Beta-Zero Thalassemia. Sickle Cell trait (AS) is an
inherited condition in which both hemoglobin A and S are made in the red blood
cells, there are always more A than S. Sickle cell trait is not a type of sickle
cell disease. People with sickle cell trait are generally healthy. Sickle cell
conditions are inherited from parents in much the same way as blood type, hair
color and texture, eye color and other physical things. The types of hemoglobin
a person makes in the red blood cells depend upon what hemoglobin genes the
person inherits from his or her parents. Like most genes, hemoglobin genes are
inherited in two sets?one from each parent (Ex. If one parent has Sickle Cell
Anemia and the other is Normal, all of the children will have sickle cell trait.
4 If one parent has sickle cell anemia and the other has sickle cell trait,
there is a 50% chance (or 1 out of 2) of having a baby with either sickle cell
disease or sickle cell trait with each pregnancy, When both parents have sickle
cell trait, they have a 25% chance (1 of 4) of having a baby with sickle cell
disease with each pregnancy). HOW DO YOU KNOW IF YOU HAVE THIS TRAIT A SIMPLE
PAINLESS BLOOD TEST followed by a laboratory technique called Hemoglobin
Electrophoresis will determine the type of hemoglobin you have. When you pass an
electric charge through a solution of hemoglobin, distinct hemoglobins move
different distances, depending on their composition. This technique
differentiates between normal hemoglobin (A), Sickle hemoglobin (S), and other
different kinds of hemoglobin (such as C, D, E,). Medical Problems Sickle cells
are destroyed rapidly in the body of people with the disease causing anemia,
jaundice and the formation of gallstones. The sickle cells also block the flow
of blood through vessels resulting in lung tissue damage (acute chest syndrome),
pain episodes (arms, legs, chest and abdomen), stroke and priapism (painful
prolonged erection). It also causes damage to most o
kidneys and liver. Damage to the spleen makes sickle cell disease patients,
especially young children, easily overwhelmed by certain bacterial infections.
TREATMENT Health maintenance for patients with sickle cell disease starts with
early diagnosis, preferably in the newborn period and includes penicillin
prophylaxis, vaccination against pneumococcus bacteria and folic acid
supplementation. Treatment of complications often includes antibiotics, pain
management, intravenous fluids, blood transfusion and surgery all backed by
psychosocial support. Like all patients with chronic disease patients are best
managed in a comprehensive multi-disciplinary program of care. Promising
Treatment Developments In search for a substance that can prevent red blood
cells from sickling without causing harm to other parts of the body, hydroxyurea
was found to reduce the frequency of severe pain, acute chest syndrome and the
need for blood transfusions in adult patients with sickle cell disease.
Hydroxyurea is a well-known drug, however its use in sickle cell disease is
relatively new and must be approached with caution. Short-term side effects must
be carefully monitored and long-term effects are still unknown POTENTIAL SAVINGS
FROM USE OF HYDROXYUREA Estimated total U.S. sickle cell patients 65,000.
Percent with severe pain 3-5 times per year 5.2%. Estimated number with frequent
severe pain 3,380. Assuming the average annual number of episodes 4. The total
number of severe pain episodes in these patients 13,520. Assuming that 50%
episodes result in hospitalization 6,760 . Assuming the average days of
hospitalization 5 . Estimated total number of hospital days for these patients
33,800. Assuming cost per day $800. Total hospitalization costs for these
patients $27,040,000. Potential savings from use of hydroxyurea in these
patients in one year $13,520,000. Estimates of sickle cell disease patients in
the U.S. is now over 70,000. In the US there were approximately 65,000
African-Americans suffering from sickle-cell disease. There were about 5,500
British sufferers. Worldwide, 100,000 babies are born with the disease annually.
Sickle cell anemia results when a person inherits two genes for sickle
hemoglobin, and is homozygous for the mutation. American-Africans are the most
likly to develope sickle cell anemia. Hemoglobin is composed of two pairs of
peptide chains: two alpha chains and two beta chains. Sickle hemoglobin results
from a point mutation in the beta-globin gene. This single nucleotide change
produces a single amino acid change: a glutamic acid at position 6 has been
changed to a valine, according to the following schedule. COOH CH -
(CH2)2-COOH Glutamic acid / NH2 COOH CH3 | CH – CH-CH3 Valine / NH2 Glutamic
acid is, as the name says, an acidic amino acid, which means it will have a
negative charge under normal body conditions and thus likes to be surrounded by
water molecules. Valine, on the other hand, is a neutral, or uncharged, amino
acid. Under normal conditions it behaves like a hydrophobic, organic molecule
and wants to hide from water. This difference makes the globin chains of
hemoglobin fold differently, especially in the absence of oxygen. Normal
hemoglobin just gives up its oxygen when it gets to the tissue that needs it,
but it retains its shape. Sickle hemoglobin, on the other hand, loses its
oxygen, and becomes relatively insoluble. In the deoxygenated form, it forms
into long arrays that come out the shape of the red cell and produce the
characteristic sickling that characterizes the disease. The insolubility of
deoxygenated (reduced) sickle hemoglobin is the basis of two rapid diagnostic
laboratory tests for sickle cell anemia. Scientists recently have had some
limited success in using genetic engineering techniques to get good copies of
the beta globin gene into people with sickle cell anemia. If they can succeed in
this endeavor, people with the disease may be cured but will still be able to
pass the genes onto their offspring.
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