Thalassemias are a group of inherited blood conditions which result in the impaired production of hemoglobin, the molecule that carries oxygen in the blood. Introduction to alpha thalassaemia city hospital, birmingham. Alphathalassemia is usually inherited in an autosomal recessive manner. Four genes are involved in making the alpha hemoglobin chain. The ucsf fetal treatment center and ucsf benioff childrens hospitals have established the first multidisciplinary center for alpha thalassemia major. The oxygen carrying capability of the red blood cells rbcs relies on hemoglobin, a tetramer protein.
Hba 2 determination is the most decisive test for bcarrier detection although it can be disturbed by the presence of dthalassemia defects. Alpha thalassemia trait a person with two working copies of the alpha globin gene has alpha thalassemia trait. Alpha thalassemia trait fact sheet arkansas department of health. Individuals who have one or two abnormal alpha globin genes have alpha thalassemia trait. Individuals with alphathalassemia trait may have symptoms of mild anemia. This condition causes mild to severe anemia, based on the type of alpha thalassemia that is inherited. Maternity alpha thalassemia diagnosis and treatment. More serious forms of alpha thalassemia will be tracked through the newborn.
The nhs sickle cell and thalassaemia screening programme also has detailed leaflets about being a beta thalassaemia carrier pdf, 804kb or a delta beta thalassaemia carrier pdf, 779kb. An individual who inherits mutations in two alphaglobin genes is a carrier of alphathalassemia and is considered to have alphathalassemia trait. Over two million people in the united states carry the genetic trait for thalassemia. A trait carrier of thalassemia will always be a trait carrier. Alpha thalassemia is a blood disorder that reduces the production of hemoglobin. Hemoglobin is the protein in red blood cells that carries oxygen to cells throughout the body. Hb constant spring is a point mutation on the alpha 2 gene at stop codon 142 taa caa term glutamine. Alphathalassemia symptoms, diagnosis and treatment. This means your child has a one 1 or 2 alpha gene deletion and has alpha thalassemia trait or is a silent carrier.
Alpha thalassemia 2 silent carrier is a result of a single gene deletion. Two mutated genes, your thalassemia signs and symptoms will be mild. Translations of brochures about thalassemia, thalassemia trait, and hemoglobin h disease are available here in pdf format for the following languages. Alphathalassemia is of particular importance to neonatologists because its clinical manifestations are present in utero and at birth. The more severe forms of alphathalassemia are found in southeast asians glader and look, 1996 and less commonly in infants of mediterranean origin, and are rare in africans. Alpha thalassemia is most commonly found in africa, the middle east, india, southeast asia, southern china, and the mediterranean region. One mutated gene, youll have no signs or symptoms of thalassemia. Health care provider hemoglobinopathy fact sheet hemoglobin. Each of the four alpha globin genes contributed to the. Arabic, cambodian, chinese, farsi, lao, tagalog, thai, and vietnamese. Alpha thalassaemia is a group of disorders of haemoglobin synthesis, caused by mutations or deletions in at least 1 of the 4 alpha globin genes, leading to variably impaired alpha globin chain production, with accumulation of the now excess and unpaired betaglobin chains. Alpha thalassemia trait may come to the attention of doctors in one of two ways.
Diagnosis is typically by blood tests including a complete blood count, special hemoglobin tests, and genetic tests. Alpha thalassemia major atm is usually fatal in utero. Detecting and reporting alpha thalassemia in newborns. They are characterized by reduced or absent production of 1 or more of the globin chains of which human hemoglobin is composed. Pediatric analyzes chromosomes in newborns and infants for changes that can explain certain birth defects or developmental delays. Alphathalassemia is a blood disorder that reduces the bodys production of hemoglobin. Dec 31, 2018 a thalassemia patient has two or more defective genes. This means they can pass on the condition of having one 1 gene missing. People with hemoglobin h disease can have an enlarged spleen, low red blood. Two missing or mutated genes is a condition called alpha thalassemia minor or having alpha thalassemia trait.
People with alpha thalassemia trait do not develop hemoglobin h disease or hydrops fetalis later in life. 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. Laboratory diagnosis of hemoglobinopathies and thalassemia. If one parent has the cis form of alpha thalassemia trait, and the other parent is a silent carrier. There are at least four forms of alpha thalassemia. One gene is missing or damaged, and the other 3 are normal. Alpha thalassemia is a group of disorders of hemoglobin synthesis, caused by mutations or deletions in at least 1 of the 4 alpha globin genes, leading to variably impaired alpha globin chain production, with accumulation of the now excess and unpaired betaglobin chains. The elongated alpha globin chains of hemoglobin constant spring alpha cs chain of hbcs are produced in low amounts such that the alpha csgene acts as a form of alpha thalassemia. Alphaglobin is expressed from four genes hba1 and hba2 on each chromosome 16 that are under the control of a 5. Normally, a second newborn screening test will not. Alphathalassaemia symptoms, diagnosis and treatment.
Is genetic counseling recommended for this patient. The alpha chain is involved in alpha thalassemia and the beta chain is affected in the more familiar beta thalassemia. Fetal blood transfusions are the only current treatment for supporting the fetus through pregnancy. The upper panel shows the globin locus that resides on chromosome 16. Newborns need chronic transfusions to replace their red blood cells. In people with the characteristic features of alpha thalassemia, a reduction in the amount of hemoglobin prevents enough oxygen from reaching the bodys tissues. The silent carrier state of thalassemia represents a mutation of one copy of the globin gene and results in no hematologic abnormalities.
The twogene deletion causes alpha thalassemia trait minor with microcytosis and. What if one parent has alpha thalassemia trait and the other parent is a silent carrier. Carrier screening to help detect the risk of having a baby with a specific inherited disorder, such as cystic fibrosis. Alphathalassemia symptoms, diagnosis and treatment bmj. 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. Potential fetal therapies are available, including transfusing the developing fetus with red blood cells to. Silent alpha thalassemia carriers have no signs or symptoms of the disease, but are able to pass thalassemia on to. Alpha globin is made by four genes, two on each strand of chromosome 16.
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. People with hemoglobin h disease can have an enlarged spleen, low red blood cell. Anyone can be a carrier of thalassaemia, but its much more common in people from certain ethnic backgrounds. Alphathalassemia genetic and rare diseases information. If both the parents are thalassemia carrier, then there is a possibility that the child born to them will have severe thalassemia. Alpha thalassemia is a condition which affects the hemoglobin in the blood.
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. Thalassemia can occur in all ethnic groups but is more common in those of southeast asian descent. Alpha thalassemia occurs frequently in people from mediterranean countries, north africa, the middle east, india, and central asia. This condition, in which one of the four alpha globin genes is missing or. 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. Affected people have anemia, which can cause pale skin, weakness, fatigue, and more serious complications. It is commonly mistaken for iron deficiency which also causes anemia. Alpha thalassemia is a general term for a group of inherited blood disorders characterized by reduced or absent production of alphaglobin subunits, resulting in low levels of hemoglobin that is otherwise fully functional. Aug 01, 2009 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. This indicates that the baby has alpha thalassemia trait. Long peptide chain is unstable and there is a very low percentage of protein present. Alpha thalassemia an overview sciencedirect topics. Despite this, it has been found that both carriers and sufferers of alpha plus thalassemia live.
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. People missing one 1 alpha globin gene aaa are called silent carriers of alpha thalassemia. Hemoglobin is the protein molecule in red blood cells that carries oxygen. Alpha thalassemia is caused by a decrease in the number of alpha globin chains being produced. A thalassemia patient has two or more defective genes. Its presence indicates that one or more of the four genes that produce alpha globin chains are dysfunctional, causing alpha. Hemoglobin barts on a newborn screen is highly suggestive of alpha thalassemia any of 4 types. However, being without a gene does not affect their health or the way they feel.
Two types of alphathalassemia can cause health problems. Alpha thalassemia nord national organization for rare. The thalassemia carrier is also known as thalassemia trait or thalassemia minor that has no direct impact on the health. Like all common globin gene disorders sickle cell trait and. The nhs sickle cell and thalassaemia screening programme also has detailed leaflets about being a beta thalassaemia carrier pdf, 804kb or a delta beta. Normal hemoglobin consists of two alpha chains and two beta chains. Thalassemia omim 141800 is the most common inherited disorder of hemoglobin hb synthesis in the world, with gene frequencies varying between 1% and 98% throughout the tropics and subtropics. 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 there are four types of alpha thalassemia, hemoglobin bart hydrops fetalis syndrome or hb bart syndrome the more severe form, hbh disease. If both the parents are thalassemia carrier, then there is a possibility. It is a genetic trait passed down from parents to children. Causes the alpha chain to be extended to 172 amino acids. When we talk about different types of thalassemia, we might be talking about one of two things. Hemoglobin is the part of the red blood cells that carries oxygen through the body.
It causes the body to make less hemoglobin than normal. The program is designed to address the complex diagnostic, prenatal, intrauterine, and perinatal management issues affecting a family with an alpha thalassemia major pregnancy. Alpha plus thalassemia can come in two forms, you may be a carrier of the gene where you have no symptoms or you may have the genetic condition. Alpha thalassemia trait causes the size of the red blood cells to be smaller than usual. Highest rates are in the mediterranean, italy, greece, turkey, west asia, north africa, south asian, and southeast asia. This is called the cis form of alpha thalassemia trait.
Alpha thalassemia can cause low red blood cell levels mild anemia and should not be confused with not having enough iron in the blood. One missing or abnormal gene makes a child a silent alpha thalassemia carrier. Alpha thalassemia silent carrierhb constant spring. Alphathalassemia information sheet integrated genetics. Jan 11, 2018 the alpha chain is involved in alpha thalassemia and the beta chain is affected in the more familiar beta thalassemia. In athalassemia, hba 2 can be lower than normal and it. If you have alpha plus thalassemia, you may find that you have some form of anaemia, which can be treated. Alphathalassaemia is a group of disorders of haemoglobin synthesis, caused by mutations or deletions in at least 1 of the 4 alphaglobin genes, leading to variably impaired alphaglobin chain production, with accumulation of the now excess and unpaired betaglobin chains. Alpha thalassemia trait results from loss of two genes. Alphathalassaemia symptoms, diagnosis and treatment bmj. Thalassemia is an inherited blood disorder in which the body makes an abnormal form of hemoglobin. While the excess beta globin chains are capable of forming soluble homotetramers beta4, hbh, they are. Alpha thalassemia major is almost uniformly fatal in utero without intervention.
Thha allasssseemmiiaa gttrraaiitt wwhhyy geett tteesstteedd. Affected individuals also have a shortage of red blood cells. People who have this condition can pass the disease on to their children. Hemoglobin barts is a tetramer of gamma fetal globin chains seen during the newborn period. The elongated alphaglobin chains of hemoglobin constant spring alpha cs chain of hbcs are produced in low amounts such that the alpha csgene acts as a form of alphathalassemia. Alpha thalassemia major atm occurs when all four genes are nonfunctioning. There are two main types, alpha thalassemia and beta thalassemia. If your baby has been identified with hemoglobin barts at birth, this means heshe is probably a health carrier.
Jul 29, 2015 alpha thalassemia is a blood disorder that reduces the bodys production of hemoglobin. The trans and cis types of alpha thalassemia trait are found most often in people whose ancestors come from southeast asia, southern china, the mediterranean, and the middle east. However, both alpha and beta thalassemia trait cause microcytic, hypochromic anaemia and are commonly. Thalassemias are prevalent worldwide with 25,000 deaths in 20. Hb hconstant spring per 100,000 births % asian population. Alpha thalassemia occurs when one or more of the 4 alphaglobin genes that make up part of the hemoglobin molecule are missing or damaged. A measurement of size, number, and maturity of different blood cells in a small blood sample. Most common of the nondeletional alpha thalassemias. Alphathalassemia is a group of disorders of hemoglobin synthesis, caused by mutations or deletions in at least 1 of the 4 alphaglobin genes, leading to variably impaired alphaglobin chain production, with accumulation of the now excess and unpaired betaglobin chains. 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. Like the silent carrier, alpha thalassemia trait is not a disease and does not affect your health. Alpha thalassemia trait is an inherited abnormality of hemoglobin that results in a very mild anemia low blood hemoglobin level and smaller size of the red blood cells reduced mcv. But you are a carrier of the disease and can pass it on to your children.
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