January 16, 2008 > An unwanted family trait
An unwanted family trait
By Brittney Hansen
Does your family have a history of blood disorders? If so, you may especially be at risk for the genetic blood disorder called thalassemia. You may carry the trait and not even know it - that's why it is important to get a blood test as soon as possible. Thalassemia comes in many different forms, so it is sometimes hard to recognize, but a simple blood test will clearly show whether or not you have the disease. The dangerous yet stealthy aspect of the disorder is that it can be passed on from generation to generation without the individuals' knowledge.
Thalassemia is a group of blood disorders which affect the production of hemoglobin, a molecule in red blood cells. Without hemoglobin the cells cannot efficiently carry oxygen to the body's tissues, leading to anemia, and if not properly treated, organ failure. Thalassemia originated in Mediterranean areas such as Italy and Greece, but it has spread all over the Asian continent. Interestingly, thalassemia aids the body's immunities against malaria; which is why thalassemia is most common in these locations. "Anywhere malaria is common, thalassemia is common," said Laurice Levine, Thalassemia Outreach Coordinator of Oakland's Children's Hospital and Research Center.
Approximately seven percent of the world's population carries the trait, but the World Health Organization (WHO) predicts that these statistics will double in the next few decades. Although most prevalent in Asian Indian and Oriental communities and in the Mediterranean, forms of thalassemia are becoming increasingly common in the United States with an estimated two million people now carrying the genetic trait through migration and intermarriage. Of these, about 5,000 in the U.S. are affected. Three hundred of these cases are in California.
The blood disorder comes in many different forms; the main two groups are called alpha and beta Thalassemia, because hemoglobin contains two protein subunit chains: alpha, and beta. Each chain is made up of several genes, and the severity of thalassemia depends on how many of the genes fail, or how many mutate.
Thalassemia minor is the slightest type of thalassemia. Although it typically does not cause any symptoms, the gene can be passed on to the next generation. If both parents are silent carriers (meaning they have the gene but may not show any signs of the disease), there is a 25 percent chance that the child will have a detectable form of thalassemia, a 50 percent chance the child will carry the trait on but have no notable symptoms, and a 25 percent chance the child will be born completely free of both the trait and the disease. With each subsequent pregnancy, the probabilities remain the same.
The worst forms of thalassemia include Hemoglobin H disease and Cooley's anemia. Symptoms include jaundice of the skin, poor appetite, severe anemia, osteoporosis, leg ulcers, and enlargement of the liver and spleen. The most severe form of thalassemia is alpha thalassemia major, also known as hydrops fetalis; if a fetus develops this disease, he or she will be stillborn, or will die shortly after birth if no treatment is administered. If the parents both know that they are thalassemia trait carriers, a prenatal test called chorionic villus sampling (CVS) can be performed to test the baby for the disease. However, if the parents are not aware that they are silent carriers, a post-birth blood test will produce a diagnosis.
Treatment for thalassemia includes blood transfusions and bone marrow transplants. In some promising cases, transplanting bone marrow eradicated the need for frequent transfusions of blood. The danger of blood transfusions is that the body cannot naturally rid itself of iron; consequently each transfusion adds to the amount of iron accumulated in the body. Iron overload affects the heart, the liver, and the endocrine organs. Over time, if too much iron is built up in the body, the organs may fail, usually resulting in death. To avoid iron overload, doctors perform iron chelation therapy, which removes excess iron from the body. This can be done using needles, or taken orally by a pill.
Blood donations are also not easy to come by. This is why it is important for everyone with a family history of blood disorders to get tested as soon as possible. There are many local facilities that test for blood disorders, including the Palo Alto Medical Foundation, the Washington Hospital Healthcare System, Kaiser Permanente, St. Rose Hospital, and the Children's Hospital and Research Center in Oakland.
For more information about thalassemia, ask your physician.