Thalassemia is a type of thalassemia that is caused by a deficiency of the alpha globin protein. The program participates in national trials and offers options for using either related and unrelated stem cell donors. This condition, in which one of the four alpha globin genes is missing or defective, generally causes no health problems because the lack of alpha globin protein is so small that there is no anemia. Carrier screening to help detect the risk of having a baby with a specific inherited disorder, such as cystic fibrosis. The content on the uptodate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Alphaglobin is expressed from four genes hba1 and hba2 on each chromosome 16 that are. Because of the complexity of the inheritance of alphathalassemia, testing and interpretation of test results is best performed by genetic professionals, including genetic counselors.
Know what are the signs and symptoms of thalassemia in adults. Alphathalassemia genetic and rare diseases information. Alpha thalassemia major is almost uniformly fatal in utero without intervention. Learn more about its symptoms and how its diagnosed. An individual with one abnormal alpha globin gene is said to be a silent carrier of alpha thalassemia. Alpha thalassemia an overview sciencedirect topics.
A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Normal hemoglobin consists of two alpha chains and two beta chains. Diagnosis of betathalassemia minor is confirmed by hba2 3. The upper panel shows the globin locus that resides on chromosome 16. Bmt program delivered the fi rst cure of alpha thalassemia major in the united states. Both aorb thalassemia carriers heterozygotes present. Diagnosis most persons with thalassemia trait are found inciden. It causes the body to make less hemoglobin than normal.
Hemoglobin barts is a tetramer of gamma fetal globin chains seen during the newborn period. Thalassemia is a treatable disorder that can be wellmanaged with blood transfusions and chelation therapy. Being a silent carrier means you dont have signs of the disease, but you can pass the damaged gene on to your child. Alpha thalassemia major atm occurs when all four genes are nonfunctioning. Heterozygotes with defects in two of the four genes result in alpha thalassemia trait, and tend to develop mild to. A person without alpha thalassemia should have four alpha globin genes. While there are many different types of thalassemia, alpha thalassemia and beta thalassemia are the. Their geographic distribution and the challenges associated with screening, diagnosis, and management suggest that. Hemoglobin is the part of the red blood cells that carries oxygen through the body. Read on to know all about its various types, symptoms and possible treatment options. The alpha and beta refer to which haemoglobin gene is affected, and which of the haemoglobin chains is faulty.
Two types of alphathalassemia can cause health problems. It is important for people with thalassemia to learn how to stay healthy. When parents are carriers of the cis deletion, there is a one in four, or 25 percent, chance with each pregnancy, to have a baby with alpha thalassemia major. Alpha thalassemia typically results from deletions involving the hba1 and hba2 genes. People who have this condition can pass the disease on. One gene is missing or damaged, and the other 3 are normal. Each type of thalassaemia alpha and beta is then classified into more types, according to how severe the condition is. Hemoglobin is a tetramer composed of 4 globin molecules. Alpha thalassemia intermedia, or hemoglobin h disease, causes. Tell the doctor if your childs newborn screening test showed barts hemoglobin. Normal alpha globin genes found on chromosome 16 people who do not produce enough alpha globin protein chains have alpha thalassemia. Potential fetal therapies are available, including transfusing the developing fetus with red blood cells to. When both parents have alpha thalassemia trait, there usually is a 25% or 1 in 4 chance in each pregnancy for the baby to have alpha.
Alpha thalassemia is found most often in people of asian origin, but it also regularly appears in people of african ancestry. Patients with this condition have a severe anemia, and often require blood transfusions to survive. Thalassemia is a genetic blood disorder that impacts the ability of the blood to get oxygen to the bodys organs. The sibling donor cord blood program, the fi rst of its kind. Affected people have anemia, which can cause pale skin, weakness, fatigue, and more serious complications. Deletional forms result in a relatively mild anemia, whereas nondeletional. There are at least 4 different and distinct alphathalassemias.
Alphathalassemia is one of the most common hemoglobin genetic abnormalities and is caused by the reduced or absent production of the alpha globin chains. Hb bart syndrome, the more severe form, is characterized by fetal onset of generalized edema, pleural and pericardial effusions. Pdf clinical classification, screening and diagnosis for. Genetic studies dna analysis to investigate deletions and mutations in the alpha and betaglobinproducing gene help in correct diagnosis and improved management in thalassemic patients. Prevention of thalassemia is based on public awareness of the disease, detection of carriers, genetic counselling, and prenatal testing. This condition causes mild to severe anemia, based on the type of alpha thalassemia that is inherited. Its presence indicates that one or more of the four genes that produce alpha globin chains are dysfunctional, causing alpha. Large deletions, point mutations, small insertiondeletion that leads to decreased transcription or an unstable transcript.
Alpha thalassemia trait may come to the attention of doctors in one of two ways. Alpha thalassemia is a result of decreased production of alpha globins. Hemoglobin h disease results from mutations of three aglobin genes. The silent carrier state of thalassemia represents a mutation of one copy of the globin gene and results in no hematologic abnormalities.
The trans form of alpha thalassemia minor is more common in people of african descent. The main types of thalassaemia are called alpha thalassaemia and beta thalassaemia. The second type of alpha thalassemia trait has two missing alpha genes on the same chromosome. Thalassemia knowledge for medical students and physicians. Initial laboratory testing should include a complete blood count with red cell indices, h plc. The diagnosis of hb bart syndrome is established in a fetus with the characteristic radiographic and laboratory features.
Abnormal pattern depends on the exact subtype see table with hemoglobin variants. Alpha thalassemia can cause low red blood cell levels mild anemia and should not be confused with not having enough iron in the blood. Physicians often mistake alpha thalassemia trait for iron deficiency anemia and incorrectly prescribe iron supplements that have no effect on the anemia. The risk of having a child with alpha thalassemia disease is dependent on the status of the parents. Beta thalassemia results from mutations in beta genes. The most severe form of alpha thalassemia, alpha thalassemia disease alpha thalassemia major can only happen when both parents have alpha thalassemia trait.
Signs and symptoms of thalassemia in adults care whizz. Heterozygotes for a single gene defect results in silent alpha thalassemia state. The analysis of the hemoglobin molecule with electrophoretic methods is an important laboratory test, which sometimes offers a definite diagnosis of the thalassemia syndrome and the hb variants. Alphathalassemia is a blood disorder that reduces the bodys production of hemoglobin. Alphathalassemia information sheet integrated genetics. Alpha thalassemia thal uh see mee uh trait is a condition that affects the amount of hemo globin in the red blood cells. Laboratory diagnosis of hemoglobinopathies and thalassemia.
The absence ofthe absence of hb h inclusions therefore does not excludeh inclusions therefore does not exclude thalassemia trait, but the presence of typical inclusions may be helpful in confirming a presumptive diagnosis. Molecular prenatal diagnosis of alphathalassemia using realtime and multiplex polymerase chain reaction methods. Alphathalassemia types, causes, diagnosis, treatment. Both of these genes provide instructions for making a protein called alphaglobin, which is a component subunit of hemoglobin people have two copies of the hba1 gene and two copies of the hba2 gene in each cell. Infants born with alpha thalassemia intermedia appear normal at birth but often develop anemia and splenomegaly by the end of their first year. Thalassemia is a blood disorder in which the body makes an abnormal form of hemoglobin. Alpha thalassemia is a condition which affects the hemoglobin in the blood. Alphathalassemia is one of the two forms of the life threatening blood disease known as thalassemia. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. Thalassemias involving delta, gamma, epsilon, and zeta chains are rare and usually not associated with significant disease outside of the neonatal period. Each of the four alpha globin genes contributed to the. Thalassemias are a group of inherited blood conditions which result in the impaired production of hemoglobin, the molecule that carries oxygen in the blood. Its causes, risk factors, complications and what are the treatment options for thalassemia. Alpha thalassemia trait fact sheet what is alpha thalassemia.
Alphathalassemia is usually inherited in an autosomal recessive manner. At conception, each sib of an individual with hb bart syndrome has a 25% chance of having hb bart syndrome, a 50% chance of having. The pathogenesis and treatment of alpha and beta thalassemia. Screening for alphathalassemia is focused on prenatal counseling and diagnosis and on newborn screening. Hematological tests being recessive condition, recognition of carriers, is essential and possible by hematological tests. Thalassemia quantitative a quantitative decrease in the production of alpha or beta globin chain. In alphathalassemia, at least one of the alpha globin genes has a mutation or aberration. In betathalassemia, the beta globin genes are affected. Laboratory diagnosis oflaboratory diagnosis of thalassemia. It is rare for africanamericans to have the cis form of alpha thalassemia, but it can happen.
96 996 61 1005 452 151 398 1137 187 616 873 744 788 768 243 1676 1077 317 538 1542 1557 673 1349 203 1124 790 501 438 555 128 31 803 829 639 128 1457