When there isnt enough hemoglobin, the bodys red blood cells dont function properly and they last shorter periods of time, so there are fewer healthy red blood cells traveling. Alphathalassemia is a blood disorder that reduces the bodys production of hemoglobin. Alpha thalassemia can occur in combination with hemoglobin s. Thalassemias are a group of inherited blood conditions which result in the impaired production of hemoglobin, the molecule that carries oxygen in the blood. Diagnosis of alphathalassemia prenatal diagnosis of deletional alphathalassemia carrier screening for individuals from highrisk populations for alphathalassemia athal overview. Know what are the signs and symptoms of thalassemia in adults. Alphathalassemia is a fairly common blood disorder that results in reduced amounts of hemoglobin, the protein in red blood cells that carries oxygen to cells in the body. Thalassemia is a type of thalassemia that is caused by a deficiency of the alpha globin protein. Thalassemia standardofcare guidelines mobile optimized 3. Alphathalassemia types, causes, diagnosis, treatment. In betathalassemia, the beta globin genes are affected.
Thalassemias are a group of inherited microcytic, hemolytic anemias characterized by defective hemoglobin synthesis. Clinically, these disorders cause a spectrum of disease that varies in severity depending on the nature of the mutations and the presence of various genetic modifiers. People with the second type of alpha thalassemia trait have 2 missing alpha globin genes on the same chromosome aa. Laboratory diagnosis oflaboratory diagnosis of thalassemia. The couple requested prenatal diagnosis for the second pregnancy. Affected people have anemia, which can cause pale skin, weakness, fatigue, and more serious complications. Therefore, alpha thalassemia occurs when there is a disturbance in production of. Alphathalassemia is particularly common among people of african, mediterranean, or southeast asian ancestry. The diagnosis of alpha thalassaemia due to deletions is implemented by the electrophoretic analysis of genomic dna digested with restriction enzymes and hybridized with. Two types of alphathalassemia can cause health problems. Pdf clinical classification, screening and diagnosis for.
Definitive diagnosis of thalassemia and hemoglobinopathies requires a comprehensive workup from complete blood count, hemoglobin analysis, and molecular studies to. Individuals with alpha thalassemia, particular the intermediate or severe forms, will benefit from referral to a thalassemia treatment center. Not the preferred firsttier molecular test for carrier screening or diagnosis of alpha thalassemia. Is fairly common combination in populations of african descent. 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. Laboratory diagnosis oflaboratory diagnosis of thalassemia yneed to start with patients individual history. Alpha thalassemia is a blood disorder that reduces the production of normal hemoglobin, the protein in red blood cells that carries oxygen to cells throughout the body. Dna sequencing of hba1hba2 alpha globin 1 and alpha globin 2 is used to identify nondeletional alphathalassemia mutations when there is a strong clinical suspicion and athal alphaglobin gene analysis, is negative. Thalassemia quantitative a quantitative decrease in the production of alpha or beta globin chain large deletions, point mutations, small insertiondeletion that leads to decreased transcription or an unstable transcript beta thalassemia results from mutations in beta genes pathogenesis a result of the free alpha subunits. The alpha chain is involved in alpha thalassemia and the beta chain is affected in the more familiar beta thalassemia. Each of the four alpha globin genes contributed to the.
Alpha and beta thalassemia american family physician. This material may not otherwise be downloaded, copied, printed. Because alpha chains are shared by fetal and adult haemoglobin the disease is manifest in. It is passed down from one or both parents through their genes. The flow chart shown in fig 4 summarizes the techniques for diagnosis of thalassemia and. Prenatal diagnosis of alphathalassemia in a twin pregnancy. Alphaglobin is expressed from four genes hba1 and hba2 on each chromosome 16 that are. Alpha thalassemia typically results from deletions involving the hba1 and hba2 genes. This signs and symptoms information for alpha thalassemia has been gathered from various sources, may not be fully accurate, and may not be the full list of alpha thalassemia signs or alpha thalassemia symptoms. Mutations in the genes that encode these proteins cause 2 major classes of thalassemia.
The dna obtained from cultured amniotic fluid cells was studied. In alphathalassemia, at least one of the alpha globin genes has a mutation or aberration. Alpha thalassemia nord national organization for rare. Alpha thalassemia, the heterozygous state with a single gene for alpha thalassemia, causes no symptoms or merely mild anemia because there is another gene still able to make alpha chains. Update on the diagnosis and management of thalassemia.
Its causes, risk factors, complications and what are the treatment options for thalassemia. Any patient with an unexplained microcytic anemia should be referred to help establish a diagnosis. Most cases of hemoglobin variants and alpha thalassemia are detected on the newborn screen, whereas beta thalassemia is not clinically apparent until about 46 months of life. Red blood cell morpho logy is altered in patients with all forms of thalassemia. Diagnostic tests for alpha thalassemia including blood tests, urine tests, swabs, diagnostic tests, lab tests, and pathology testing. Usually, patients with hemoglobin h disease are clinically well and survive without any. Pdf on mar 21, 2012, vefik arica and others published alpha thalassemia disorders find, read and cite all the. Carriers of alphathalassemia do not need any treatment.
Increased cardiothoracic ratio of the left twin of a pregnancy discordant for fetal homozygous. Children with alpha thalassemia major may have a swollen abdomen or symptoms of anemia or failure to thrive. Listed herein are the content contributors to the thalassemia standard of care guidelines. The woman had a first pregnancy terminated in the delivery of a hydropic fetus due to homozygous. Alphathalassemia is characterized by a deficit in the production of the. This is called the cis form of alpha thalassemia trait. Persons with the thalassemia trait have a normal life expectancy. Alphathalassemia pregnancies are rising in north america and require prenatal counseling, overall community education, and welldeveloped intrauterine management plans.
Patients with thalassemia minor or intermedia should be offered genetic counseling because offspring of. Thalassaemia disorders in humans caused by the deficiency of the alpha chain of hemoglobin have been well documented and validated throughout the world, by various stepwise diagnostic strategies and techniques. Signs and symptoms of thalassemia in adults care whizz. Prevention of thalassemia is based on public awareness of the disease, detection of carriers, genetic counselling, and prenatal testing. Laboratory diagnosis oflaboratory diagnosis of thalassemia dr. Impaired 1, 2, 3, or 4 alpha globin chain productions can lead to a comparative excess of the beta globin chains. Thalassemia is a defect in alphachain synthesis in which one alpha trait, two. This lowers the amount of oxygen that cells receive, causing various health problems, including anemia.
The diagnosis of alphathalassaemia due to deletions is implemented by the electrophoretic analysis of genomic dna digested with restriction enzymes and hybridized with. Deletional forms result in a relatively mild anemia, whereas nondeletional. People with hemoglobin h disease can have an enlarged spleen, low red blood cell. Thalassemias involving delta, gamma, epsilon, and zeta chains are rare and usually not associated with significant disease outside of the neonatal period. Normal hemoglobin consists of two alpha chains and two beta chains. The program is designed to address the complex diagnostic, prenatal, intrauterine, and perinatal management issues affecting a family with an alpha thalassemia major pregnancy. Diagnosis most persons with thalassemia trait are found inciden. Silent carriers of alpha thalassemia and persons with alpha or beta thalassemia trait are asymp tomatic and require no treatment. Alpha thalassemia an overview sciencedirect topics. Laboratory diagnosis of hemoglobinopathies and thalassemia. Have less hb s present than those with sickle cell trait. Alphathalassemia genetic and rare diseases information. The ucsf fetal treatment center and ucsf benioff childrens hospitals have established the first multidisciplinary center for alpha thalassemia major. Pdf at present, thalassemia diseases are classified into.
The trans form of alpha thalassemia trait aa is common in africanamericans 2030 percent and people of african descent. Furthermore, signs and symptoms of alpha thalassemia may vary on. Thalassemia is a group of inherited blood disorders caused by defects in one or more genes responsible for producing the globin chains in hemoglobin. There are four types of alpha thalassemia, hemoglobin bart hydrops fetalis syndrome or hb bart syndrome the more severe form, hbh disease, silent carrier state and trait. Inherited haemoglobin disorders, including thalassaemia and sicklecell disease, are the most common monogenic diseases worldwide. The most severe form of alpha thalassemia, alpha thalassemia disease alpha thalassemia major can only happen when both parents have alpha thalassemia trait. Alpha thalassemia intermedia, or hemoglobin h disease, causes. What if one parent has alpha thalassemia trait and the other parent is a silent carrier. The condition is caused by the disruption of one or more of the four resident homologous hemoglobin alpha genes. In most cases, alpha thalassemia is diagnosed before a childs second birthday or through newborn screening, a blood test given when the child is first born. 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. Hemoglobin h disease results from mutations of three aglobin genes. Hypochromic microcytes and target cells are the main features in asymptomatic ind ividuals.
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