what is sickle cell disease?

Question

the molecular basis of sickle cell disease

Answer 1

For the Molecular Biology of Sickle Cell Anemia go to:

http://www.nslc.wustl.edu/sicklecell/part2/molecular.html

What Is Sickle Cell Anemia?

Sickle cell anemia is a serious disease in which the body makes abnormally shaped red blood cells. Normal red blood cells are smooth and round like a doughnut without a hole. They move easily through blood vessels to carry oxygen to all parts of the body. In sickle cell anemia, the body produces red blood cells that are shaped like a sickle (or crescent). These "sickle cells" are hard and sticky and they don't move easily through blood vessels. They tend to get stuck and block the flow of blood to the limbs and organs. This can cause pain, organ damage, and a low blood count (anemia).

Sickle cell anemia is an inherited (genetic) disorder. People who have sickle cell anemia are born with it. It is a lifelong disease.

Sickle-shaped red blood cells

The sickle-shaped red blood cells tend to get stuck in blood vessels, blocking the flow of blood.

Sickle cell anemia affects millions of people. Effective treatments exist for the symptoms and complications of the disease, but in most cases there is no cure. (Some researchers believe that bone marrow transplantation may offer a cure in a small percentage of cases.) Over the past 30 years, doctors have learned a great deal about the disease. They know what causes it, how it affects your body, and how to treat many of the complications. Today, with good health care, many people with the disease:

* Are in reasonably good health much of the time
* Live fairly normal lives
* Live 40 to 50 years or more

Anemia

Anemia is the term for having a shortage of red blood cells in your blood. In sickle cell anemia, this shortage of red blood cells occurs because sickle cells do not last very long. Red blood cells are produced in the spongy marrow inside the large bones of the body. The bone marrow constantly makes new red blood cells to replace old ones. Normal red blood cells last about 120 days in the bloodstream and then die. Sickle cells die much faster, usually after only about 10 to 20 days. The bone marrow can't make new red blood cells fast enough to replace the dying ones, so anemia (low level of red blood cells) results.

Sickle Cell Trait Versus Anemia

The condition called sickle cell trait is different from sickle cell anemia. A person with sickle cell trait does not have the disease but carries the gene that causes the disease. People with sickle cell trait can pass the gene on when they have children.

What Are the Signs and Symptoms of Sickle Cell Anemia?

The signs and symptoms of sickle cell anemia are different in each person. Some people have mild symptoms. Others have very severe symptoms and are often hospitalized for treatment.

The most common signs or symptoms are related to:

* Anemia
* Pain when sickle-shaped red blood cells block the flow of blood to an organ
* Other more specific symptoms

The general signs or symptoms of anemia are:

* Fatigue (feeling very tired)
* Paleness
* Jaundice (yellowing of the skin and eyes)
* Shortness of breath

Pain is the symptom of sickle cell anemia that most people know. In both children and adults, pain may result from blocked flow of blood and oxygen. Painful events may occur in any body organ or joint. Some patients have these painful crises less than once a year. Others may have 15 or more crises in a year. The pain can be acute (sudden), chronic (long lasting), or a mixture of the two.

* Acute pain is the most common type of pain. This is sudden pain that can range from a mild ache to very severe pain. The pain usually lasts from hours to a few days. With complications or poor treatment, the pain can last for weeks.
* Chronic pain usually lasts 3 to 6 months or longer. Chronic pain can be hard to bear and mentally draining. This pain may severely limit daily activities.
* Mixed pain is a combination of both acute and chronic pain.

Other complications of sickle cell anemia include:

* Hand-foot syndrome. When the small blood vessels in hands or feet are blocked by sickle cells, pain and swelling can occur, along with fever. One or both hands and/or feet may be affected at the same time. This may be the first symptom of sickle cell anemia in infants. Pain may be felt in the many bones of the hands and feet. Swelling usually occurs on the back of the hands and feet and moves into the fingers and toes.
* Eye problems. The retina, a thin layer of tissue at the back of the eye, receives and processes visual images. When the retina does not get enough blood, it can weaken and cause problems. These problems can be serious enough to cause blindness.
* Infections. Both children and adults with sickle cell anemia have a hard time fighting infections. The spleen is an organ in your body that helps fight infection. In sickle cell anemia, the spleen can become damaged and unable to do its job. Infants and young children with a damaged spleen are more likely to get infections that can kill them within hours or days. Pneumonia is the most common cause of death in young children with sickle cell anemia. Meningitis, influenza, and hepatitis are other infections that are common in people with sickle cell anemia.
* Acute chest syndrome. This is a life-threatening problem of sickle cell anemia. This syndrome is similar to pneumonia. It is caused by infection or by sickle cells trapped in the lungs. Patients usually have chest pain, fever, and an abnormal chest x ray.
* Delayed growth and puberty in children. Children with sickle cell anemia often grow more slowly and reach puberty later than other children. The slow rate of growth is caused by a shortage of red blood cells (anemia). Adults with sickle cell anemia often are slender or small in size.
* Sores (ulcers) on the legs. Sickle cell ulcers usually begin as small, raised, crusting sores on the lower third of the leg. Leg sores occur more often in males than in females and usually appear between ages 10 and 50. The cause of leg ulcers is unclear. There can be just one ulcer or many. Some heal rapidly, but others persist for years or come back after healing.
* Stroke. The sickle-shaped red blood cells may stick to the walls of the tiny blood vessels in the brain. This can cause a stroke. This type of stroke occurs mainly in children. The stroke can cause learning disabilities or more severe problems.
* Gallstones. Gallstones form in the gallbladder when there is too much bilirubin in the body. Bilirubin is made when red blood cells break down. People with gallstones may have steady pain that lasts for 30 minutes or more in the upper right side of the belly, under the right shoulder, or between the shoulder blades. The pain may occur after eating fatty meals. The patient may have nausea, vomiting, fever, sweating, chills, clay-colored stool, and yellowish color of the skin or whites of the eyes.
* Priapism. Males with sickle cell anemia may have painful and unwanted erections called priapism. This happens because the sickle cells stop blood flow out of an erect penis.

Answer 2

It is a mutation in the Hemoglobin molecule. There are several types of hemoglobin molecules. Infants have type A, most adults have type F and so on. Patients with sickle cell have type S. The problem with this is that when type S hemoglobin is deprived of oxygen it causes the red blood cell to shange shape and turn into a sickle shape. Normally RBC's are round and are able to change shape to fit through narrow capillaries. Once they sickle they can no longer change shape. This causes a sickle cell patient to experience great pain as blood cells begin to back up with pressure in the capillaries in the extremities. Usually it's activated when the patient is exercising and becomes short of breath or for any other reason they would be short of breath. The interesting thing about Type S hemoglobin is that it's resistant to malaria...which is probably why African people developed this trait. It helps them fight off malaria, but causes sickle cell.

Once the person has had a sickle cell crisis the treatment is to give them oxygen to stop the cells from sickling. Unfortunately, those that have already sickled are lost. Gradually the spleen and liver filter them out leaving the patient with fewer RBC's and a lower Hemoglobin which is what anemia is.

Answer 3

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Answer 4

Sickle cell disease is a genetic disorder in which the person who has it has a single incorrect nucleotide in his/her DNA which codes for the production of Hemoglobin. The effect is that all the hemoglobin produced by this person has a shape that doesn't allow for the proper loading of oxygen (a sickle shape).
Interestingly, if the person has inherited one sickle cell gene from one parent and one normal from the other, then ther person is much less affected by the symptoms of the disease, but highly resistant to to Malaria. This has caused a natural selection for people with one of the genes in parts of Africa where malaria is common. In fact, black people have a much higher chance of being carriers than people of other races.

Answer 5

Sickle cell anemia is treatable, but the only cure is by bone marrow transplantation with a genetically-related donor. Since the defect that causes SCA is in the progenitors of red blood cells that reside in the bone marrow, the diseased marrow must first be destroyed by radiation and drugs, and then reconstituted with normal bone marrow cells from a related donor.

Answer 6

Its a disease of the Afros. or blacks The cell is sickle in shape rather than round and concave and does not carry oxygen well.
In many cases it is incompatible with ongoing life

Answer 7

It is anemia. When their are a lot of defective RBC(Sickle shaped) cells in your blood. Due to it blood looses its capacity of carrying oxygen to your cells.

Answer 8

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Answer 9

it's error in the genes that r responsible for formation of heamoglobin..leading to decrease ability to carry oxygen..needs frequent blood transfusion

Answer 10

In college i did my final term paper on it.......it's a form of anemia.