 | Holly Alexander, PhD is a clinical scientist in the Via Christi Regional Medical Center Laboratory. She received her PhD from the University of Connecticut and completed a post-doctoral fellowship in Medical and Public Health Microbiology at the California Department of Health Services in Berkeley, Calif. She is a diplomat of the American Board of Medical Microbiology. She can be reached at Holly_Alexander@via-christi.org |
Health & Medicine
2003-02-01 15:30:00
What is Sickle Cell Anemia?
: What is Sickle Cell Anemia? What causes it?
ANSWER: Red blood cells are an important component of blood that transport oxygen from the lungs to all the cells of the body. Hemoglobin, the molecule in a red cell that actually carries the oxygen, is made up of 2 pairs of smaller molecules called alpha globin and beta globin. Everyone inherits one gene for alpha globin and one for beta globin from each of his or her parents.When a person inherits an abnormal alpha or beta globin gene from one parent and a normal gene from the other parent, the person may not realize that he or she is a "carrier" of the disease. These individuals rarely have symptoms, but they could pass the abnormal gene to their children. However, when a person inherits an abnormal gene from each parent, the abnormal hemoglobin molecule doesn't carry oxygen as efficiently as the normal molecule. There are many different abnormal alpha or beta globin genes. Sickle Cell disease is due to one of the most common abnormalities in the beta globin gene. It changes the shape of the hemoglobin molecule and causes the red blood cell containing it to change from the normal doughnut shape to a sickle shape, hence the name. These abnormally-shaped cells are more likely to be destroyed as they pass through the blood vessels and organs of the body. This causes severe pain and damages organs such as the lungs, kidney, liver and spleen. The abnormal hemoglobin associated with Sickle Cell disease is most common in equatorial Africa. That is why it is most common in African-Americans, but people from the Middle East, India and the Mediterranean regions also have an increased prevalence of abnormal hemoglobin diseases, including Sickle Cell disease. These abnormal hemoglobins seem to offer some protection against malaria, which is thought to be the reason they developed in this part of the world.In the US, Sickle Cell disease occurs in about 1:15,000 babies, but African Americans have a higher incidence of about 1:4,000. Most states, including Kansas, have a program to screen babies at birth to detect abnormal hemoglobins (as well as several other genetic diseases) so that the child can be cared for to try to decrease the long-term complications of the disease. These screening programs have been very successful in providing care to those who are affected and in decreasing deaths due to Sickle Cell disease.
