Beta Trait and Beta Thalassemia Disease

Beta Thalassemia Trait Beta thalassemia disease is an inherited blood When you have one working copy of the beta disorder. It is more often found in people with globin and one non-working copy you have Italian, Greek, Asian, or African heritage, but it can beta thalassemia trait. Your body makes less of be found in people with ancestry from any part of the beta chains, but is still able to make plenty of the world. To understand this condition, it helps to A. This is not a disease and does not know more about how your blood is made. affect your health. This trait causes the red blood cells to be smaller than usual. Sometimes, this is Hemoglobin mistaken for low iron levels (iron-deficiency Your blood contains millions of red blood cells. ). However, taking an iron supplement does Each of your red blood cells has hemoglobin, which not change the size of the red blood cells. gives blood its red color and carries oxygen throughout your body. Hemoglobin is made by A person with beta thalassemia trait will never combining a “heme” portion (iron) and a “globin” develop beta thalassemia disease. The importance portion (). The iron comes from the food you of identifying beta thalassemia trait is that it helps eat and your body makes the globins. find couples whose children may be born with beta There are different kinds of hemoglobin that the thalassemia disease. body can make. The most common kind in an adult is . For hemoglobin A, your body puts Beta Thalassemia Disease (Beta two “alpha” globin chains together with two “beta” thalassemia major) globin chains. If you don’t make enough beta Beta thalassemia disease is a lifelong condition chains it is called beta thalassemia. that can include serious health problems, but it affects each person differently. The most common The instructions for making globin chains are part form of the disease requires regular blood of the genetic information you inherit from your transfusions and extensive medical care due to parents. Genetic instructions are called . You severe anemia. Starting treatment early in life helps inherit your genes in pairs, with one copy of each gene coming from each parent. One particular decrease the symptoms of the disease, but gene, the beta globin gene, is responsible for telling repeated transfusions can cause medical problems the body how to make beta globin chains. In beta from iron build-up in the body. thalassemia, the gene for making beta globin chains doesn’t work normally. Beta thalassemia disease has been cured using bone marrow transplantation, but the procedure has serious risks and requires a suitable donor.

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ADA Review: May 2018 Page 1 of 3

Beta Thalassemia Trait and Beta Thalassemia Disease

Other forms of hemoglobin disease Beta thalassemia disease can only happen Most of the time beta thalassemia disease when both parents have beta thalassemia trait. happens when both parents have beta When both parents have beta thalassemia trait, thalassemia trait. But sometimes one parent there is a 25% (or 1 in 4) chance in each carries a different blood trait, such as pregnancy for the baby to have beta or hemoglobin S (sickle cell). thalassemia disease. There is a 75% (or 3 in 4) When one of these other chance that the baby will not have this disease. combines with beta thalassemia trait, the result is a different form of hemoglobin disease. When one parent has beta thalassemia trait Other diseases that can be related to beta and the other parent has a related blood trait thalassemia include: (hemoglobin E or hemoglobin S), there is a • Hemoglobin E-beta thalassemia disease 25% (or 1 in 4) chance in each pregnancy for • Sickle-beta thalassemia disease the baby to have a hemoglobin disease. There Some forms of hemoglobin disease have more is a 75% (or 3 in 4) chance that the baby will medical problems than others. not have this disease.

Inheritance and prenatal diagnosis. It is possible to test the developing baby for If you have beta thalassemia trait, it is possible beta thalassemia disease as early as 10 weeks to pass it to your children. However, the chance in pregnancy. If testing shows the baby has for a hemoglobin disease depends on the kind beta thalassemia disease, parents can choose of blood trait in both parents. Blood tests can whether or not to continue the pregnancy. Early find out exactly what trait you have, if any. detection can also allow the family to prepare Then, your genetic counselor can tell you the for the birth of a baby who may need specialty chance that a child of yours could inherit beta care in infancy. thalassemia disease or another form of hemoglobin disease. In California, all babies are routinely tested for beta thalassemia disease through the Newborn When only one parent has beta thalassemia Screening Program. Beta thalassemia trait is trait and the other does not have a blood trait, not usually detectable in the newborn period. there is essentially no chance of having a baby with any form of beta thalassemia disease. However, each child has a 50% (or 1 in 2) chance to inherit beta thalassemia trait from the parent. Genetics.kp.org

Page 2 of 3 Beta Thalassemia Common Inheritance Patterns

One parent with beta thalassemia trait KEY TO SYMBOLS

AA Hemoglobin A - Two working beta globin genes AA AB AB Beta thalassemia trait - One working beta globin gene - One non-working beta globin gene BB Beta thalassemia disease - Two non-working beta globin genes

AE Hemoglobin E trait - One working beta globin gene - One hemoglobin E gene AA AB AA AB

BE E-Beta thalassemia disease Trait Trait - One non-working beta globin gene Each pregnancy has a 50% chance to have trait. - One hemoglobin E gene NOT at risk for disease

One parent with beta thalassemia trait and Both parents with beta thalassemia trait One parent with hemoglobin E trait

AB AB AE AB

AA AB AB BB AA AB AE BE Trait Trait Beta Trait Trait E-Beta Thalassemia Thalassemia Disease Disease Each pregnancy has a 25% chance to have Each pregnancy has a 25% chance to have beta thalassemia disease E-beta thalassemia disease

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This information is not intended to diagnose health problems or to take the place of medical advice or care you receive from your physician or other health care professional. © 2010, The Permanente Medical Group, Inc. All rights reserved. R egional Genetics Department. Last reviewed: February 2017 Page 3 of 3