The most common genetic disorders in people of Asian descent are thalassemia, a variety of blood disorders, and sickle cell anemia. Thalassemia affects approximately 1 in 20 Asian people, and sickle cell anemia affects about 1 in every 500, particularly those from Southeast Asia.
The most common cause of thalassemia is a defect in the production of beta globin or alpha globin. Beta globin makes up one half of hemoglobin, which is a protein in red blood cells. Alpha globin makes up the other half. Therefore these defects are referred to as beta thalassemia or alpha thalassemia.
Alpha thalassemia is a blood disease resulting in severe anemia, and sometimes death in a fetus or newborn child. The severity of the disease varies tremendously depending on the exact genes inherited.
An individual with one abnormal alpha globin gene is said to be a silent carrier of alpha thalassemia, which usually causes no health problems in that individual, as there is generally no anemia present. A person with two abnormal alpha globin genes has the alpha thalassemia trait. This is often confused with iron deficiency anemia, but more iron in the diet or iron supplements will not fix the problem. Patients with the alpha thalassemia trait generally only experience mild anemia, and often do not show symptoms.
However, when one parent has the alpha thalassemia trait, and the other parent is a silent carrier, there is a 25% chance that their child will be born with hemoglobin H disease, in which three or four alpha globin genes are abnormal. Hemoglobin H disease can cause severe anemia, an enlarged spleen and bone deformities.
If both parents carry the alpha thalassemia trait, there is a 25% chance that their child will be born with alpha thalassemia major, a disease in which all four alpha globin genes are abnormal. Most children born with alpha thalassemia major die before or soon after birth.
Beta thalassemia is a defect in the production of beta globin. Beta thalassemia is similar to alpha thalassemia in the way it affects people and how it is passed along to to children. Beta thalassemia can cause anemia in children, and often requires frequent blood transfusions to combat. Children with beta thalassemia often have bone deformities and experience frequent breakages or fractures. Sufferers of beta thalassemia can sometimes develop heart disease because of the disorder.
Sickle Cell Anemia
Sickle cell anemia is a disease which mutates the red blood cells into a sickle shape that look like a capital “C.” When the blood cells sickle, it becomes very difficult for them to move through the blood vessels, and they sometimes get stuck. Children whose parents both have sickle cell traits have a 25% chance to inherit sickle cell anemia. Sickle cell anemia can cause severe pain, serious infections and organ damage. The average life span for sufferers of the disease is between 40 and 60 years old.
Testing for Genetic Disorders
Genetic testing in the form of a blood or saliva test is often offered to perspective parents who are worried about passing genetic diseases on to their children. Genetic testing does have its limitations, however. A positive result does not necessarily mean the disease will be passed on to children, or that the patient will develop the disease himself.