Saturday, April 19, 2014

An Understanding Of Sickle Cell Anemia Prevention

By Anita Ortega

Sickle Cell Disease is an inherited disorder of red blood cells, called erythrocytes, and the most common genetic disease in the United States. Normal red blood cells are round and concave in the middle; they flow easily through the bloodstream. Diseased erythrocytes, on the other hand, are sticky and bent into a sickle shape, like the sharp implements that are used to cut through sugar cane. Sickle cell anemia prevention is best discussed with a genetic counselor.

In order for someone to develop the disease, both parents must carry the recessive trait for a specific type of hemoglobin. This trait is called AS. In this case, there is one chance in four that their offspring will inherit the disease. There is also half a chance that they will carry the AS trait and one chance in four that they will neither carry the trait nor have the disease. If one parent has normal hemoglobin, Type AA, and the other has AS, there is half a chance that each child will have the trait but not the disease.

African Americans are disproportionately affected by the disease. One out of every ten or twelve carry the trait and one in 400 or 500 newborns have the disease. What is not commonly known is that the disease affects people from other nationalities as well. The incidence in newborns of Hispanic origin is about half that of the African American population. Other nationalities that are susceptible to the disease include Italy, Latin America, Arabs, Greeks and Asiatic Indians.

We already know that the SA gene is recessive. If this is the case, why is it such a prevalent disease? The reason for this is that the AS trait confers greater survival with respect to malaria, a deadly condition caused by a parasite carried by mosquitoes and affecting half the world's population. Up until very recently, the reason for this was completely unknown.

In 2011, a group of scientists published a paper in the prestigious journal, Cell, that began to shed light on the molecular mechanisms that AS people are protected from malaria, a deadly disease that affects half the world's population. Unfortunately, this is of little consolation to sufferers of SCD.

A lot of the symptoms and signs of SCD are common to other forms of anemia. These include dizziness, headaches, extreme fatigue, shortness of breath, pale skin, jaundiced eyes and coldness in the extremities. The condition is also characterized by sudden episodes of debilitating pain throughout the entire body.

An SCA crisis occurs when the errant erythrocytes stick together and cut off blood flow, causing damage to major organs (lungs, liver and kidneys). This is also what causes the bouts of unbearable pain. A crisis may go on for hours and then resolve spontaneously or it may persist for days, up to a week or longer.

Currently in the United States, all newborn babies are routinely tested for the AS trait and for SCD. This paves the way for early treatment of the condition. So far, the only of preventing SCD is by having a frank discussion with a genetic counselor and making sometimes difficult decisions regarding family planning.

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