The most prevalent genetic disorder in the USA today is Sickle Cell Anemia (SCA) and affects the red blood cells, also known as erythrocytes or rbcs. Healthy rbcs are concave in the middle. This is because fetal cells lose their nuclei upon birth. This ennucleation causes the cell to sink in on itself. In SCA, the crescent-shaped erythrocytes are rapidly destroyed. This forces a rapid production of new ones. These cells are forced out before they are mature, causing them to retain their nuclei. Couples who believe they may carry the genes for the disease should consult a genetic counselor about sickle cell anemia prevention.
Both parents must carry the sickle cell trait for hemoglobin (Type AS) for the offspring to inherit the disease. If this is the case, there is a 25% chance that the child will have the disease, 50% chance that he or she will carry the trait and a 25% chance that they will have neither the trait nor the disease. If one parent has normal hemoglobin (Type AA) and the other has Type AS, there is a 50% chance that each child will carry the trait, but they will not get 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.
Many of the signs and symptoms of the disease are related to the anemia. These include fatigue, dizziness, headaches, shortness of breath, cold hands and feet, paler than normal skin and jaundiced eyes. Sickle cell disease is often punctuated by crises, in which the subject is suddenly in severe pain throughout the 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.
All newborns in the United States are routinely tested for AS. This opens the door for early treatment of the disease. At the moment, the only way to prevent sickle cell disease is through genetic counseling and family planning. Research is ongoing to find ways of making it possible for individuals who have the disease to live comfortable and productive lives.
Both parents must carry the sickle cell trait for hemoglobin (Type AS) for the offspring to inherit the disease. If this is the case, there is a 25% chance that the child will have the disease, 50% chance that he or she will carry the trait and a 25% chance that they will have neither the trait nor the disease. If one parent has normal hemoglobin (Type AA) and the other has Type AS, there is a 50% chance that each child will carry the trait, but they will not get 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.
Many of the signs and symptoms of the disease are related to the anemia. These include fatigue, dizziness, headaches, shortness of breath, cold hands and feet, paler than normal skin and jaundiced eyes. Sickle cell disease is often punctuated by crises, in which the subject is suddenly in severe pain throughout the 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.
All newborns in the United States are routinely tested for AS. This opens the door for early treatment of the disease. At the moment, the only way to prevent sickle cell disease is through genetic counseling and family planning. Research is ongoing to find ways of making it possible for individuals who have the disease to live comfortable and productive lives.
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