The forms of beta thalassaemia with normal haemoglobin a2. Thalassemia quantitative a quantitative decrease in the production of alpha or beta globin chain. Alpha thalassemia alpha thalassemia is the result of changes in the genes. Family history and ancestry are factors that increase the risk of beta thalassemia. Nathan division of hematology of the department of medicine of the childrens hospital medical center, boston, massachusetts 02115. Individuals with thalassemia major usually present within the first two years of life. 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. There are different types of thalassaemia, which can be divided into alpha and beta thalassaemias. The alpha chain is involved in alpha thalassemia and the beta chain is affected in the more familiar beta thalassemia.
It is normal for people whose ancestors come from these areas to carry mild alpha thalassaemia, so you should not worry about it. Disorders of beta globin, such as sickle cell disease and beta thalassemia major, are not clinically apparent until several months of age, when the switch from hemoglobin f to hemoglobin a synthesis reveals the defect. Beta thalassemia syndromes are a group of hereditary disorders characterized by a genetic deficiency in the synthesis of beta globin chains. Along with patient care, medical research is a primary focus at the comprehensive thalassemia center at ucsf benioff childrens hospital oakland. Thalassemia is due to a deficit or absent production of. What does it mean to be a carrier of alpha plus thalassemia. Thalassemias occur most often among people of italian, greek, middle eastern, southern asian, and african descent. The trans form of alpha thalassemia trait aa is common in africanamericans 2030 percent and people of african descent. Detection of sickle alpha or beta0thalassemia by studies of. If the extent of inclusion formation in thalassemia is related to the. Thalassemia in arab populations alpha and beta thalassemia are endemic in almost all arab countries probably due to the historical presence of malaria in the region and the high level of consanguinity. While the excess beta globin chains are capable of forming soluble homotetramers beta4, hbh, they are.
Soon after birth, the majority of hemoglobin is comprised of iron and four globin chains, two alpha globin and two beta globin chains. Normally, alpha globin chain is made by four genes two from each parent, two on each strand of chromosome 16. Thalassemias are a group of inherited blood conditions which result in the impaired production of hemoglobin, the molecule that carries oxygen in the blood. It is probably the most common monogenic gene disorder in the world and is especially frequent in mediterranean countries. Beta thalassemia trait and beta thalassemia disease other forms of hemoglobin disease most of the time beta thalassemia disease happens when both parents have beta thalassemia trait. Being a silent carrier means you dont have signs of the disease, but you can pass the damaged gene on to your child. Deletion of 1 allele alfa talasemia in the silent form, 2 alleles in alphathalassemia trait, and 3 alleles in hbh. Thalassemia alpha and beta thalassemia see online here thalassemia is a major cause of microcytic anemia due to an imbalance in the production of. Alpha thalassemia alpha thalassemia is due to impaired or absent production of alpha globin chains, which leads to a relative excess of gamma globin chains in the fetus and newborn, and excess beta globin chains in children and adults. In 60 nonthalassemic controls, the beta alpha specific activity ratio was 1. Highperformance liquid chromatography hplc is the investigation used for the diagnosis of beta thalassemia. Beta thalassemia major is the most severe form of beta thalassemia in which the. Clinical management of thalassemia major consists in regular. The other two chains are also identical to one another but differ from the alpha chains and are termed the beta chains.
Alphathalassaemia is inherited as an autosomal recessive disorder characterised by a microcytic hypochromic anaemia, and a clinical phenotype varying from almost asymptomatic to a lethal haemolytic anaemia. Jan 01, 2004 the use of intrauterine transfusions to sustain the viability of fetuses with homozygous alpha thalassemia has created a new population of patients with severe thalassemia and has raised new and complex issues in genetic counseling for parents with alpha thalassemia trait. Normal alpha globin genes found on chromosome 16 people who do not produce enough alpha globin protein chains have alpha thalassemia. In thalassemia, there is a defect in the synthesis of. In beta thalassemia, the gene for making beta globin chains doesnt work normally. Thalassemia hematology american society of hematology. Physicians often mistake alpha thalassemia trait for iron deficiency anemia and incorrectly prescribe iron supplements that have no effect on the anemia. Thalassaemia of intermediate severity resulting from the interaction between alpha and betathalassaemia. Thalassaemia of intermediate severity resulting from the.
Jan 11, 2018 the alpha chain is involved in alpha thalassemia and the beta chain is affected in the more familiar beta thalassemia. Affected people have anemia, which can cause pale skin, weakness, fatigue, and more serious complications. In contrast, gamma globin mutations are evident in the neonate and then disappear as gamma globin synthesis wanes. If you have one, your body makes fewer healthy red blood cells and less hemoglobin. Beta thalassemia beta thal trait, beta thal intermedia, beta thal major is caused. Laboratory diagnosis of hemoglobinopathies and thalassemia. A total of 6946 subjects were enrolled for evaluating alphabeta thalassemia from 2012 to 2018. Diagnosis diagnosis of alpha thalassemia is through the globin chain synthesis studies. This is called the cis form of alpha thalassemia trait. The two main types are called alpha and beta thalassemia, depending on which part of globin chain is produced in reduced amounts victor et al. Depending on family history, if a persons parents or grandparents had beta thalassemia major or intermedia, there is a 75% 3 out of 4 probability see inheritance chart at top of page of the mutated gene being inherited by an offspring. The two main types are called alpha and beta thalassemia, depending on.
Its also possible to be a carrier of thalassaemia, also known as having the thalassaemia trait. Alpha thalassemia is a general term for a group of inherited blood disorders characterized by reduced or absent production of alpha globin subunits, resulting in low levels of hemoglobin that is otherwise fully functional. Beta thalassemia trait and beta thalassemia disease. Alpha and beta thalassemia american family physician. Other types include beta thalassaemia intermedia, alpha thalassaemia major and haemoglobin h disease. Hemoglobin, which carries oxygen to all cells in the body, is made of two different parts, called alpha and beta. Beta thalassemia major also called cooleys anemia is a serious illness.
It is passed down from one or both parents through their genes. There are two main types, alpha thalassemia and beta thalassemia. Dec 10, 2019 thalassemias are inherited blood disorders. Thalassaemia minor can refer to people with either alpha or beta thalassaemia. Thalassemia thalassemia is an inherited blood disorder in which the body produces an abnormal form of hemoglobin which results in excessive destruction of red blood cells and further leads to anemia. Because they have one functioning copy of the gene, their health is not affected by beta thalassaemia. Alpha thalassemia trait causes the size of the red blood cells to be smaller than usual. Alpha thalassemia nord national organization for rare. Two types of alpha thalassemia can cause health problems. People with the second type of alpha thalassemia trait have 2 missing alpha globin genes on the same chromosome aa.
Alpha thalassemia intermedia, or hemoglobin h disease, causes. Thalassemias slide 1 by the end of the lecture, the student. Alphathalassemia genetic and rare diseases information. Symptoms of beta thalassemia are due to reduced production of the betaglobin chains. The thalassemias are classified according to the type of globin polypeptide chain that is underproduced.
Alpha thalassemia normally, alpha globin chain is made by four genes two from each parent, two on each strand of chromosome 16. Hemoglobin is a protein that carries oxygen to the body. Large deletions, point mutations, small insertiondeletion that leads to decreased transcription or an unstable transcript. Jun, 2019 the severity of alpha and beta thalassemia depends on how many of the four genes for alpha globin or two genes for beta globin are missing. Your body makes less of the beta chains, but is still able to make plenty of. We have applied globin synthesis and free alpha chain pool studies of peripheral blood to characterize hematologic disorders where alpha or beta thalassemia was present in combination with hbs or hbc. The symptoms of thalassemia major generally appear before a childs second birthday. Jul 29, 2015 alpha thalassemia is a blood disorder that reduces the bodys production of hemoglobin.
Apr 25, 2019 homozygous beta thalassemia is a severe, transfusion dependent anaemia that also causes infertility. The problem in the thalassemias is with globin production. Diagnosis is typically by blood tests including a complete blood count, special hemoglobin tests, and genetic tests. One gene is missing or damaged, and the other 3 are normal. Carrying the gene for alpha plus thalassaemia does not cause any illness, however it. Like the silent carrier, alpha thalassemia trait is not a disease and does not affect your health. Thalassemia major is the most severe form of beta thalassemia. Health care provider hemoglobinopathy fact sheet hemoglobin. There are two main forms of beta thalassemia as beta thalassemia major and beta thalassemia minor. But sometimes one parent carries a different blood trait, such as hemoglobin e or hemoglobin s sickle cell.
Beta thalassemia results from mutations in beta gene s. Genetic testing to confirm a diagnosis of alpha or beta thalassemia is. Thalassemia is a treatable disorder that can be wellmanaged with blood transfusions and chelation therapy. There are two primary types of thalassemia disease. Nov 04, 2018 for those with alpha thalassemia trait or silent carriers with only mild anemia from time to alfa talasemia, no medical treatment is necessary. Alpha thalassemia or hemoglobin constant spring trait moderate barts alpha thalassemia trait produces a moderate level of barts and typically results from the dysfunction of two alpha genes either due to gene deletions or a specific change in the alpha gene that produces elongated alpha globin and. Introduction to alpha thalassaemia city hospital, birmingham. When thalassemia is called alpha or beta, this refers to the part of hemoglobin that isnt being made. Beta thalassemia trait when you have one working copy of the beta globin gene and one nonworking copy you have beta thalassemia trait. The severity of alpha and beta thalassemia depends on how many of the four genes for alpha globin or two genes for beta globin are missing. Thalassemia research and care at ucsf benioff childrens hospital oakland. Get a printable copy pdf file of the complete article 1. Beta thalassemia results from mutations in beta genes.
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