If both parents are missing at least one alpha globin allele, each of their children are at risk of having hb bart syndrome or hydrops fetalis, hemoglobin h hbh disease, or alpha thalassemia trait. People with hemoglobin h disease can have an enlarged spleen, low red blood. However, many people with this type of thalassemia have no signs or symptoms. Despite this, it has been found that both carriers and sufferers of alpha plus thalassemia live. An individual with one abnormal alpha globin gene is said to be a silent carrier of alpha thalassemia. Hemoglobin barts on a newborn screen is highly suggestive of alpha thalassemia any of 4 types.
Alpha thalassemia is a condition which affects the hemoglobin in the blood. A blood disorder, thalassemia is not one disease but rather a group of disorders that have a single feature in common. The inheritance of alphathalassemia is complex because the condition involves two genes. It is a genetic trait passed down from parents to children. This condition, in which one of the four alpha globin genes is missing or. 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. Individuals with alphathalassemia trait may have symptoms of mild anemia. Hemoglobin is the protein in red blood cells that carries oxygen to cells throughout the body. The fate of excess betaglobin chains within erythropoietic cells in alphathalassaemia 2 trait, alphathalassaemia 1 trait, haemoglobin h disease and haemoglobin qh disease. This trait can only cause a problem if your partner has alpha zero thalassaemia trait in which case your children might inherit hbh disease explained below.
Alphaglobin is expressed from four genes hba1 and hba2 on each chromosome 16 that are under the control of a 5. Thalassemias are prevalent worldwide with 25,000 deaths in 20. 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. If one parent has the cis form of alpha thalassemia trait, and the other parent is a silent carrier. People who have alpha thalassemia trait can have mild anemia. People who have this condition can pass the disease on. The more severe forms of alphathalassemia are found in southeast asians glader and look, 1996 and less commonly in infants of mediterranean origin. Alpha thalassemia trait fact sheet what is alpha thalassemia. The more mutated genes, the more severe your thalassemia.
In people with the characteristic features of alpha thalassemia, a reduction in the amount of hemoglobin prevents enough oxygen from reaching the bodys tissues. Alpha thalassemia affects the amount of hemoglobin in the red blood cells. In alpha thalassemia, the heterozygous state with a single gene for alpha thalassemia is innocuous or harmless. People with alpha thalassemia trait only have 2 genes for alpha globin, so their bodies make slightly less hemoglobin than normal. This is called the trans form of alpha thalassemia trait.
Introduction to alpha thalassaemia city hospital, birmingham. This condition causes mild to severe anemia, based on the type of alpha thalassemia that is inherited. Thalassemia is a treatable disorder that can be wellmanaged with blood transfusions and chelation therapy. Aug 01, 2009 alpha thalassemia typically results from deletions involving the hba1 and hba2 genes. Normal hemoglobin consists of two alpha chains and two beta chains. This is called the cis form of alpha thalassemia trait. 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 ucsf fetal treatment center and ucsf benioff childrens hospitals have established the first multidisciplinary center for alpha thalassemia major.
Enable javascript to view the expandcollapse boxes. Parents who have been told that their newborn had barts hemoglobin at birth should tell their health care provider. 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. 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 fact sheet arkansas department of health. Alpha thalassemia nord national organization for rare. Hb will be normal in alphathalassemia silent carrier and may be slightly low in alphathalassemia trait.
Alphathalassemia symptoms, diagnosis and treatment bmj. Genetic counseling resources for hemoglobin disorders and traits. Beta thalassemia trait and beta thalassemia disease. Alpha thalassemia trait and beta thalassemia trait. Maternity alpha thalassemia diagnosis and treatment. When the words trait, minor, intermedia, or major are used, these words describe how severe the thalassemia is. Health care provider hemoglobinopathy fact sheet hemoglobin. Northern californias comprehensive thalassemia center at childrens hospital oakland, delivers quality care to thalassemia patients.
It is one of the few nih funded centers in the nation, and at the. People with the second type of alpha thalassemia trait have 2 missing alpha globin genes on the same chromosome aa. Although the hemoglobin barts causes no problems and goes away after several months, it is very specific for a baby having alpha thalassemia trait. 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. Two gene deletion only two genes are inherited for the production of alpha globin chains. Nov 22, 2019 in thalassemia, the production of either the alpha or beta chains are reduced, resulting in either alpha thalassemia or beta thalassemia. Alpha thalassemia is most commonly found in africa, the middle east, india, southeast asia, southern china, and the mediterranean region. It causes the body to make less hemoglobin than normal. If either the alpha or beta part is not made, there arent enough building blocks to make normal amounts of hemoglobin. 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. Laboratory diagnosis of hemoglobinopathies and thalassemia. Therefore, there are 4 alleles that produce alphaglobin, the protein that results from these genes. Abstract thalassemias are genetic disorders inherited from a persons parents. Normally, people have four genes for alpha globin with two genes on each chromosome.
Apr 30, 2020 thalassemias are inherited blood disorders. Dec 27, 2018 the alpha chain is involved in alpha thalassemia and the beta chain is affected in the more familiar beta thalassemia. Hemoglobin is a protein that carries oxygen to the body. The molecular basis for alphathalassemia is usually deletion of one or more of the four alpha globin genes. Adult hemoglobin hemoglobin a is made of alpha and beta globins. Alpha thalassemia trait results from loss of two genes. Alpha thalassemia trait causes the size of the red blood cells to be smaller than usual. Alpha thalassemia is caused by alterations mutations in two adjacent genes, the hba1 and the hba2 genes.
This indicates that the baby has alpha thalassemia trait. Individuals who have one or two abnormal alpha globin genes have alpha thalassemia trait. Every person has two copies of the hba1 gene one from each parent and two copies of the hba2 gene also one from each parent. The first type of alpha thalassemia trait has one alpha gene missing on each chromosome. Beta thalassemia major was first described in the medical literature in 1925 by an american physician named thomas cooley. Alpha thalassemia trait is an inherited abnormality of hemoglobin that results in a very mild anemia low blood hemoglobin level and smaller size. Hemoglobin is the protein molecule in red blood cells that carries oxygen. Patients with this condition have small red cells and a mild anemia but they do not have clear symptoms. Molecular diagnosis of thalassemias and hemoglobinopathies. Alpha globin is made by four genes, two on each strand of chromosome 16. Two missing or mutated genes is a condition called alpha thalassemia minor or having alpha thalassemia trait. Although the hemoglobin barts causes no problems and goes away after several months, it is very specific for a.
Thha allasssseemmiiaa gttrraaiitt wwhhyy geett tteesstteedd. People with alpha thalassemia trait only have two genes for alpha globin, so they make slightly lower. A loss of one alpha globin allele is found in alpha thalassemia silent carriers. A small amount of barts hemoglobin is identified at birth, however it soon disappears. Persons with beta thalassemia major are diagnosed during infancy. It is important for people with thalassemia to learn how to stay healthy. They look and feel normal but may be discovered upon routine testing hillman and ault, 2002. Alpha thalassemia thal uh see mee uh trait is a condition that affects the amount of hemo globin in the red blood cells. Alphathalassemia genetic and rare diseases information. When both parents have beta thalassemia trait, there is a 25% or 1 in 4 chance in each pregnancy for the baby to have beta thalassemia disease. 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. Alphathalassemia symptoms, diagnosis and treatment.
An individual who inherits mutations in two alphaglobin genes is a carrier of alphathalassemia and is considered to have alphathalassemia trait. Hemoglobin is the part of the red blood cells that carries oxygen through the body. Jul 29, 2015 the different types of alpha thalassemia result from the loss of some or all of these alleles. Thalassemia is an inherited blood disorder in which the body makes an abnormal form of hemoglobin. These individuals typically have no thalassemia related signs or symptoms. Hemoglobin is the part of the red blood cells that carries. When the words trait, minor, intermedia, or major are used, these words describe how. Alpha thalassemia is found most often in people of asian origin, but it also regularly appears in people of african ancestry. Alphathalassemia is usually inherited in an autosomal recessive manner. Since the father has hemoglobin e trait and the mother has some type of. Alpha thalassemia an overview sciencedirect topics.
For each of the 2 genes, one allele is inherited from a persons father. The two gene deletion causes alpha thalassemia trait minor with microcytosis and usually no anemia. Alpha thalassemia 2 silent carrier is a result of a single gene deletion. The molecular basis for alphathalassemia is usually deletion of one or more of the. For those with alpha thalassemia trait or silent carriers with only mild anemia from time to time, no medical treatment is necessary. Alpha thalassemia minor and beta thalassemia minor, also known as alpha thalassemia trait or beta thalassemia trait, are common conditions in many demographics. Nov 01, 2005 alphathalassemia is usually inherited in an autosomal recessive manner. There are no symptoms or at most mild anemia, because there is another gene still able to make alpha chains. A trait carrier of thalassemia will always be a trait carrier. Alpha thalassemia major is so severe that affected fetuses will develop anemia due to the lack of functioning red blood cells needed to provide oxygen. 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. Northern california comprehensive thalassemia center ucsf benioff childrens hospital oakland 747 52nd street, oakland ca 94609 phone. What if one parent has alpha thalassemia trait and the other parent is a silent carrier.
Alpha thalassemia trait is characterized by two functional genes that code for the production of alpha globins. Alpha thalassemia trait a person with two working copies of the alpha globin gene has alpha thalassemia trait. This means that you have one missing alpha haemoglobin gene. People with hemoglobin h disease can have an enlarged spleen, low red blood cell. People have two copies of the hba1 gene and two copies of the hba2 gene in each cell. 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. People with alpha thalassemia trait may have unusually small, pale red blood cells and mild anemia. If you have one, your body makes fewer healthy red blood cells and less hemoglobin. Pallor, irritability, growth retardation, abdominal swelling, and jaundice appear during the sec. This means you have two missing alpha haemoglobin genes out of the normal four alpha genes. Affected individuals may have a mutation or combination of mutations in one gene, two genes, three genes, or all four copies of these genes. If you have alpha plus thalassemia, you may find that you have some form of anaemia, which can be treated. Established in 1991, with more than 200 patients on active followup and over 800 patient visits every year, the center is one of the largest thalassemia programs in the country. Beta thalassemia disease can only happen when both parents have beta thalassemia trait. Treatments for thalassemias depend on the type and severity of the disorder. Progressive fetal anemia can lead to heart failure because of the stress on the fetal heart, which can be seen on ultrasound as fetal hydrops. Alpha thalassemia typically results from deletions involving the hba1 and hba2 genes. Anyone can be a carrier of thalassaemia, but its much more common in people from certain ethnic backgrounds. A loss of two of the four alpha globin alleles results in alpha thalassemia trait.
It is commonly mistaken for iron deficiency which also causes anemia. A measurement of size, number, and maturity of different blood cells in a small blood sample. It will not make you ill, but if your partner also has alpha zero thalassaemia trait, your children might inherit a severe condition called hb barts explained below. In alpha thalassemia, the severity of thalassemia you have depends on the number of gene mutations you inherit from your parents. People who have this condition can pass the disease on to their children.
Like the silent carrier, alpha thalassemia trait is not a disease and does not affect your health. Alpha thalassemia is a blood disorder that reduces the production of hemoglobin. Alphathalassemia is of particular importance to neonatologists because its clinical manifestations are present in utero and at birth. 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. Like all common globin gene disorders sickle cell trait and. The fate of excess betaglobin chains within erythropoietic cells in alpha thalassaemia 2 trait, alpha thalassaemia 1 trait, haemoglobin h disease and haemoglobin qh disease. Alpha thalassemia trait may come to the attention of doctors in one of two ways. 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.