Beta Thalassemia
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What is beta thalassemia?
Beta thalassemia is a type of inherited blood disorder that can cause anemia (a low number of red blood cells). It affects a person's ability to produce hemoglobin, the protein in red blood cells that delivers oxygen to all parts of the body.
Signs and symptoms of beta thalassemia are severe in the form of the disorder known as thalassemia major and less severe in the form called thalassemia intermedia. Signs and symptoms of thalassemia major appear in the first 2 years of life. Infants become pale and listless, have a poor appetite, grow slowly, and often develop jaundice (yellowing of the skin). The spleen, liver, and heart may also be enlarged. Adolescents with the severe form may experience delayed puberty. Individuals with thalassemia intermedia may have no symptoms or mild symptoms through childhood and adolescence.
How common is beta thalassemia?
Worldwide, beta thalassemia is considered a fairly common blood disorder, affecting thousands of infants each year. Beta thalassemia occurs most frequently in Mediterranean countries, North Africa, the Middle East, India, and southeast Asia. In North America, the disorder is less common; an estimated 750-1000 people have beta thalassemia.
What genes are related to beta thalassemia?
Mutations in the HBB gene cause beta thalassemia.
The HBB gene produces one of the subunits of hemoglobin, called beta hemoglobin or the beta chain. Mutations in the HBB gene can reduce or abolish the production of beta-hemoglobin, leading to abnormal hemoglobin that cannot perform its function as an oxygen carrier.
How do people inherit beta thalassemia?
Beta thalassemia major and thalassemia intermedia are inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered. Most often, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder. Sometimes, however, carriers of the altered HBB gene have a mild anemia referred to as thalassemia minor.
In a small percentage of families, the HBB mutation is inherited in an autosomal dominant manner. In these cases, one copy of the altered gene in each cell is sufficient to cause the disorder.
Source: National Institutes of Health
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Reports from Khon Kaen University add new data to research in thalassemia
2009 JUL 6 - (NewsRx.com) -- New research, 'Analysis of fetal blood using capillary electrophoresis system: a simple method for prenatal diagnosis of severe thalassemia diseases,' is the subject of a report. According to recent research published in the European Journal of Haematology, "Prenatal diagnosis of severe alpha-and beta-thalasssemia diseases is usually performed by DNA analysis. To establish a simple method, we have evaluated the reliability of prenatal diagnosis by fetal blood analysis using automated capillary electrophoresis system." "Forty-seven fetal blood specimens collected by cordocentesis at 18-28 wk of gestation were analyzed by the capillary electrophoresis system (Sebia). Fetal DNA was analyzed for respective thalassemia alleles by PCR. Among 47 fetuses, 20 were at risk for the Hb Bart's hydrops fetalis. DNA analysis identified four cases of homozygous alpha degrees -thalassemia (SEA type). Hb analysis by the capillary electrophoresis demonstrated a major peak of Hb Bart's (78.4-81.3%), Hb H (0.8-1.4%) and minor peaks of presumably embryonic Hbs. No Hb F and Hb A was observed. The level of Hb Bart's was found to be 3.4-5.8% in unaffected heterozygote whereas normal fetus had no Hb Bart's. Among the remaining 27 fetuses at risk for Hb E-beta-thalassemia, DNA analysis identified 12 affected fetuses. Hb analysis showed Hb F (94.9-98.9%) and Hb E (1.1-1.8%) without Hb A in all cases. The levels of Hb A were found to be (4.3-7.2%), (1.0-5.5%) and (2.1-3.9%) in normal, heterozygous Hb E and heterozygous beta-thalassemia fetuses, respectively. Affected and unaffected fetuses could be easily distinguished," wrote H. Srivorakun and colleagues, Khon Kaen University. The researchers concluded: "Capillary electrophoresis system is a simple and automated procedure for accurate prenatal diagnosis of severe thalassemia diseases which could readily be performed in routine setting." Srivorakun and colleagues published their study in European Journal of Haematology (Analysis of fetal blood using capillary electrophoresis system: a simple method for prenatal diagnosis of severe thalassemia diseases. European Journal of Haematology, 2009;83(1):57-65). For additional information, contact H. Srivorakun, Biomedical Sciences Program, The Graduate School, Khon Kaen University, Khon Kaen, Thailand. The publisher's contact information for the European Journal of Haematology is: Blackwell Publishing Inc., 350 Main St., Malden, MA 02148, USA. Keywords: Thailand, Khon Kaen, Capillary Electrophoresis, DNA, Edema, Hematology, Hydrops Fetalis, Thalassemia. This article was prepared by Hematology Week editors from staff and other reports. Copyright 2009, Hematology Week via NewsRx.com.
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