Epidemiology
What is Sickle Cell Disease?
Sickle Cell disease (or anemia) is a group of inherited red blood cell disorders. Normal red blood cells are round like doughnuts, and they move through small blood tubes in the body to deliver oxygen. Sickle red blood cells become hard, sticky and shaped like sickles used to cut wheat. When these hard and pointed red cells go through the small blood tube, they clog the flow and break apart. This can cause pain, damage and a low blood count, or anemia.
What makes the red cell sickle?
There is a substance in the red cell called hemoglobin that carries oxygen inside the cell. One little change in this substance causes the hemoglobin to form long rods in the red cell when it gives away oxygen. These rigid rods change the red cell into a sickle shape.
What is sickle cell trait?
Sickle cell trait is a person who carries one sickle hemoglobin producing gene inherited from their parents and one normal hemoglobin gene. Normal hemoglobin is called type A. Sickle hemoglobin called type S. Sickle cell trait is the presence of hemoglobin AS on the hemoglobin electrophoresis. This will NOT cause sickle cell disease. Other hemoglobin traits common in the United States are AC and AE traits.
Distribution
Sickle cell is found in Africans, Turks, Greeks, Saudi Arabians, Egyptians, Iranians, Italians, Latin Americans, and Asiatic Indians. Sickle Cell Disease is present in 1 out of every 400 African-Americans in the U.S. while Sickle Cell Trait is present in 1 out of every 12 African-Americans in the U.S. It is the most common genetic disease in the African-American community.
Complications
Complications from the sickle cells blocking blood flow and early breaking apart include:
1. Pain episodes
2. Strokes
3. Increased infections
4. Leg ulcers
5. Bone damage
6. Yellow eyes or jaundice
7. Early gallstones
8. Lung blockage
9. Kidney damage and loss of body water in urine
10. Painful erections in men (priapism)
11. Blood blockage in the spleen or liver (sequestration)
12. Eye damage
13. Low red blood cell counts (anemia)
14. Delayed growth
Research
Hydroxy or Hydrea has been found to do the following in adult sickle cell patients:
1. Reduce pain events by one half.
2. Reduce hospital admissions by one half.
3. Reduce the need for transfused blood.
4. Raised the patient's hemoglobin average by one gram
Bone Marrow Transplantation is for those patients with enough complications from sickle cell disease to take the risk of this procedure, that replaces the patient's bone marrow with a near perfect donor marrow, usually from a brother or sister. This procedure involves destroying the patient's bone marrow with medications and transfusing the donated marrow as a new "seed". The patient will start making the same red blood cells that the donor makes and not the red blood cells with the sickle hemoglobin.
STOP Study - The Stroke prevention study uses cranial Doppler radar to record the sound of blood flow in the blood vessels supplying blood to the brain. Any blockage will increase the noise of the blood flow and this may be an early sign that a stroke may occur. Special studies can be done with tools like the MRI to look at blood flow in the brain. Strokes may be prevented by a chronic blood transfusion program.
Adhesion blockers - Medications that prevent red blood cells from sticking and thus help to reduce pain and damage to tissues
Healthy Living
Prevention FARMS
The things that cause red blood cells to sickle are: dehydration, fever, low oxygen, stress, cold exposure, and slow blood flow. Preventative care such as the FARMS method tries to prevent these known causes of cell sickling.
Sickle cell patient should be under the care of a medical team that understands sickle cell disease. All newborn babies detected with sickle cell disease should be placed on daily penicillin to prevent serious infections. All of the childhood immunizations should be given plus the pneumococcal vaccine. Parents should know how to check for a fever because this signals the need for a quick medical checkup for serious infection. The following are general guidelines to keep the sickle cell patient healthy:
1. Taking the vitamin folic acid (folate) daily to help make
new red cells.
2. Daily penicillin until age six to prevent serious infection.
3. Drinking plenty of water daily (8-10 glasses for adults).
4. Avoiding too hot or too cold temperatures.
5. Avoiding over exertion and stress.
6. Getting plenty of rest.
7. Getting regular check-ups from knowledgeable health care providers.
Sickle Cell Model
The purpose of the Sickle Cell Stella Model is to track the disease progression of Sickle Cell over the course of time. It incorporates the use random mating, and Mendelian genetics with the existing populations of Normal, Sickle Cell Trait, and Sickle Cell Disease persons and then tracks their numbers over time. The model allows users to artificially alter the existing of Normal, Sickle Cell Trait, and Sickle Cell Disease ratios and the randomness of the model. At the same time the user can also monitor the numbers of Normal, Sickle Cell Trait, and Sickle Cell Disease persons in the final populations. Preliminary conclusions indicate the ratios of Normal, Sickle Cell Trait, and Sickle Cell Disease persons remained constant over at least 500 cycles. However, the model should be run over a much longer time period (i.e. 10,000 cycles) in order to see if the individual populations will significantly change.
References
Motulsky AG. Frequency of Sickling Disorders in US Blacks. New England Journal of Medicine. 1973; 288:31.
Sergeant G. Sickle Cell Disease. Oxford: Oxford University Press 1985.
The Sickle Cell Information Center. URL: http://www.emory.edu/PEDS/SICKLE/
(7 Jun.1998).