Sickle Cell Anemia (SCD)

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Sickle Cell Anemia (SCD)

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Sickle Cell Anemia (SCD)

Sickle cell anemia (also called sickle cell disease or SCD) is an inherited disease in which a person does not have enough healthy red blood cells to carry oxygen throughout the body.
Sickle cell disease is the most common genetic disease in the world and is most common in people whose families come from Africa, South or Central America (especially Panama), Caribbean islands, Mediterranean countries (such as Turkey, Greece, and Italy), India, and Saudi Arabia.
In the United States, about 1 in every 500 African Americans are born with the disease. Hispanic Americans also are affected at a rate of about 1 in 1,000 to 1,400.

Sickle cell disease symptoms and diagnosis

Normal healthy red blood cells are flexible and round, move easily through blood vessels and carry oxygen to all parts of your body. In sickle cell disease, red blood cells are not round. Instead they are curved like a crescent, or sickle. This is because the hemoglobin in the red blood cell is abnormal. The sickle-shaped red blood cells cannot move easily and can become stuck in small blood vessels, blocking them.
As a result, the blood supply to that part of the body is restricted. Organs that do not receive normal blood flow will become damaged over time. Restricted blood flow is what causes the complications of sickle cell disease, which can range from mild fatigue to more severe symptoms such as stroke, infections, and pain in the bones and chest requiring treatment in the hospital. The complications vary from person to person, with some having to see their doctor often and others less so.
There is no cure for most people with sickle cell disease, as they are born with the abnormal hemoglobin. However, there are treatments and medicines that control or prevent the health problems caused by the disease.

Symptoms

The signs and symptoms of sickle cell disease vary. Some people have mild symptoms. Others have very severe symptoms and often are hospitalized frequently for treatment. Sickle cell disease is present at birth, but many infants don't show any signs until after 4 months of age. The most common signs and symptoms are linked to anemia and pain. Other signs and symptoms are linked to organ complications from the disease.
Signs and symptoms of sickle cell disease include:
  • Fatigue (most common symptom)
  • Shortness of breath
  • Dizziness
  • Headache
  • Coldness in the hands and feet
  • Pale skin
  • Chest pain

Sickle cell and pain

Sudden pain affecting different parts of the body is a common symptom of sickle cell disease. This pain is called a "sickle cell crisis." Sickle cell crises often affect the bones, lungs, abdomen, arms, legs, and joints.
A sickle cell crisis occurs when sickled red blood cells form clumps in the bloodstream. (Other cells also may play a role in this clumping process.) These clumps of cells block blood flow through the small blood vessels in the limbs and organs. This can cause pain and organ damage.
The pain from sickle cell crisis can be acute (sudden) or chronic (long-lasting), but acute pain is more common. Acute pain comes suddenly and can range from mild to very severe. The pain usually lasts from hours to a few days. Chronic pain often lasts for weeks to months. Chronic pain can be hard to bear and mentally draining. This pain may severely limit daily activities, work and education.
Almost all people who have sickle cell disease have painful crises at some point in their lives. Some have these crises less than once a year. Others may have 15 or more pain crises in a year.

Diagnosis

Early diagnosis of sickle cell disease is very important so that children who have the condition can get proper treatment. Almost all states in the United States now test newborns for sickle cell disease with a blood test. Anyone can request a sickle cell test.
Although a blood test can diagnose sickle cell disease, doctors are not able to predict how seriously the disease will affect individual patients. There is no simple test to identify which patients will have almost normal life spans, very few painful crises, and little damage to their body due to their sickled cells, and which patients will have frequent, painful crises and drastically reduced life spans. For this reason, deciding on a course of treatment can be very difficult.

Treatment options

Sickle cell disease has no widely available cure. However, certain medicines such as hydroxyurea, antibiotics and blood transfusions (for some) can relieve symptoms of this disease.  In addition, when complications happen these will require treatment and sometimes require a stay in the hospital. For some with sickle cell disease, these treatments are sufficient to control their disease, and it allows them to live like someone without sickle cell disease, even though they have the disease. For others this is not the case. It is for this group of persons who do not respond to medical treatment, a transplant of bone marrow or cord blood offers the possibility of curing the disease.

Bone marrow or cord blood transplant for SCD

Bone marrow or cord blood transplant can offer the chance for a possible cure for patients with severe sickle cell disease, but it has serious risks and may not be an option for all patients. A bone marrow or cord blood transplant replaces the abnormal cells in the bone marrow with healthy blood-forming cells from a family member or an unrelated donor or cord blood unit.
A transplant may be a good option for patients who have a suitably matched donor or cord blood unit and are healthy enough to tolerate a transplant. [1, 2] The donor for a transplant must closely match the patient's tissue type. The best donor is usually a sibling. Each sibling has a 25% chance of being a match.
However, since sickle cell disease is inherited, many people with sickle cell disease do not have a healthy matched donor in their family. For patients who do not have a suitable donor in their family, doctors may work with the National Marrow Donor Program ® (NMDP) to find a matching adult volunteer donor or cord blood unit from our Be the Match Registry ® and other registries around the world.


Making treatment decisions

If you or your child has sickle cell disease, it is important to see a doctor who is an expert in the disease. If your doctor has not treated other patients with sickle cell disease, ask him or her to refer you to an expert for consultation.
A doctor who is an expert in sickle cell disease can talk with you about your treatment options and explain the possible risks and benefits. Whatever treatment you and your doctor decide on, you may choose to be part of a clinical trial. Clinical trials help doctors gain knowledge that can improve treatments for patients in the future. Even standard treatments continue to be studied in clinical trials.
The time between diagnosis and transplant can affect transplant outcomes. To improve you or your child's chances of a successful transplant, you and your doctor can plan ahead. A consultation with a transplant doctor can help determine whether a transplant is a good option for you.

Sickle cell trait

People who inherit a sickle cell gene from one parent and a normal hemoglobin gene from the other parent have a condition called sickle cell trait. Sickle cell trait is different from sickle cell disease. People who have sickle cell trait don't have the disease, but they have one of the genes that cause it. Like people who have sickle cell disease, people who have sickle cell trait can pass the gene to their children.

More information

You can get more information about sickle cell disease from these disease-specific or government health organizations:

References

  1. Bernaudin F, Socie G, Kuentz M, et al. Long-term results of related myeloablative stem-cell transplantation to cure sickle cell disease. Blood. 2007; 110(7):2749-2756.
    http://bloodjournal.org/cgi/content/full/110/7/2749  
  2. Panepinto JA, Walters MC, Carreras J, et al. Matched-related donor transplantation for sickle cell disease: report from the Center for International Blood and Transplant Research. Br J Haematol. 2007; 137(5):479-485.
    http://www3.interscience.wiley.com/journal/118517611/abstract 

Contributing editors

Shalini Shenoy, M.D., St. Louis Children's Hospital, Washington University
Mary Eapen, M.D., Medical College of Wisconsin, Milwaukee, Wis.