Sickle-Cell-Anemia

= Sickle Cell Disease =

Description:
Sickle cell is a disease in which your body produces abnormally shaped red blood cells. The cells are shaped like a crescent or sickle. A genetic mutation causes sickle cell anemia.

Genetic Background/significance:
Sickle cell anemia is caused by a missense mutation in the //HBB// gene. A missense mutation is a single base change in the sequence of a gene. Instead of the gene reading GAG, it reads GTG. So the A and the T are switched. The effect of this single change is to make the hemoglobin temporarily polymerize to make fibers after it has released the oxygen that it carries around the body. This changes the shape of the red blood cells so that they don't flow so easily - it makes them sticky, especially in small blood vessels. This can cause pain and lead to organ damage.

The HBB gene is located on chromosome 15, making the mutation an autosomal recessive mutation.

Sickle cell conditions are inherited from parents in much the same way as blood type, hair color and texture, eye color and other physical traits. 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 set, one from each parent. o People with sickle cell anemia inherited the sickle cell gene from both their parents · In people with sickle cell anemia, their red blood cells contain hemoglobin S; which is abnormal · Sickle cell anemia has a pattern to it; its seen mostly in African Americans

Symptoms:
· 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 organs including the spleen, kidneys and liver. Damage to the spleen makes sickle cell disease patients, especially young children, easily overwhelmed by certain bacterial infections. · The most common symptom of anemia is fatigue (feeling tired or weak). Other signs and symptoms of anemia may include: o Shortness of breath o Dizziness o Headaches o Coldness in the hands and feet <span style="font-family: Arial,Helvetica,sans-serif;">o Paler than normal skin or mucous membranes (the tissue that lines your nose, mouth, and other organs and body cavities) <span style="font-family: Arial,Helvetica,sans-serif;">Treatment: <span style="font-family: Arial,Helvetica,sans-serif;">· Treatment of complications often includes antibiotics, pain management, intravenous fluids, blood transfusion and surgery all backed by psychosocial support <span style="font-family: Arial,Helvetica,sans-serif;">o Blood transfusions help benefit sickle cell disease patients by reducing recurrent pain crises, risk of stroke and other complications. Because red blood cells contain iron, and there is no natural way for the body to eliminate it, patients who receive repeated blood transfusions can accumulate iron in the body until it reaches toxic levels. It is important to remove excess iron from the body, because it can gather in the heart, liver, and other organs and may lead to organ damage. Treatments are available to eliminate iron overload.

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<span style="font-family: Arial,Helvetica,sans-serif;">Sources: <span style="font-family: Arial,Helvetica,sans-serif;">· [] <span style="font-family: Arial,Helvetica,sans-serif;">· http://www.answers.com/topic/missense-mutation
 * <span style="font-family: Arial,Helvetica,sans-serif;">http://www.chemguide.co.uk/organicprops/aminoacids/dna6.html