China
Africa
Explore chapters and articles related to this topic
Beta Thalassemia
Published in Charles Theisler, Adjuvant Medical Care, 2023
Beta thalassemia is an inherited blood disorder that reduces the production of hemoglobin. Low levels of hemoglobin can lead to a lack of oxygen in many parts of the body. Beta thalassemia is classified into two types depending on the severity of symptoms: thalassemia major, also known as Cooley’s anemia, and thalassemia intermedia. Of the two types, thalassemia major is more severe.
Carrier Screening For Inherited Genetic Conditions
Published in Vincenzo Berghella, Obstetric Evidence Based Guidelines, 2022
Whitney Bender, Lorraine Dugoff
Alpha-thalassemia results from a gene deletion of two or more copies of the four alpha-globin genes on chromosome 16. It is common among individuals of Southeast Asian, African, West Indian, and Mediterranean ancestry. Deletion of two genes, alpha-thalassemia trait, causes a mild hemolytic anemia. The deletions may occur on the same chromosome (cis aa/-) or on two different chromosomes (trans a-/a-). Individuals of Southeast Asian descent are more likely to carry the cis configuration compared to their African counterparts. Individuals with alpha-thalassemia trait are at increased risk for having a child with a more severe form of alpha-thalassemia. Hemoglobin H disease is caused by the deletion of three alpha-globin genes. Affected individuals have mild to moderate hemolytic anemia. Alpha-thalassemia major (Hb Bart disease) results from the absence of functional alpha-globin genes. Fetal hydrops and intrauterine fetal demise is the expected outcome in these cases due to the inability to produce functional HbF. Hemoglobin Bart disease does not usually occur in fetuses of alpha-thalassemia carriers of African origin, since individuals of African descent usually have the trans-configuration genotype. See Chap. 14 in Maternal-Fetal Medicine Evidence Based Guidelines.
Blood transfusion in patients requiring long-term support
Published in Jennifer Duguid, Lawrence Tim Goodnough, Michael J. Desmond, Transfusion Medicine in Practice, 2020
The survival and quality of life of patients with thalassaemia major have changed dramatically since the introduction of regular transfusion regimes. Most patients start transfusions in the first year of life, in the presence of symptoms and signs of severe anaemia, usually when haemoglobin drops below 7 g/dl; however, some children may not require blood until the age of 3–4 years. Current standards recommend the maintenance of a pretransfusion haemoglobin level of 9.5 g/dl and a mean haemoglobin level of 12 g/dl. Such regimes result in normal growth and development, as well as suppression of endogenous erythropoiesis, which prevents bone marrow expansion and skeletal deformities. Delay in the development of splenomegaly and improved cardiac reserve are also achieved by regular transfusions; furthermore, despite an overall increase in the number of blood units transfused, iron overloading is not accelerated, because of the suppression of intestinal iron absorption.55 In practice, the ‘hypertransfusion’ regime translates into transfusing 1–3 units of red cells every 3–4 weeks, with non-splenectomized patients having about 30% higher requirements than splenectomized ones.56
Research Progress of Cell-Free Fetal DNA in Non-Invasive Prenatal Diagnosis of Thalassemia
Published in Hemoglobin, 2023
Dewen Liu, Chen Nong, Fengming Lai, Yulian Tang, Taizhong Wang
Thalassemia is a common hemolytic disease caused by abnormal globin synthesis due to mutations or deletions of HBA1, HBA2 or HBB genes, resulting in abnormal morphology and life cycle of red blood cells. The Globin website (https://globin.bx.psu.edu/cgi-bin/hbvar/counter) currently records more than 500 types of thalassemia mutations and deletions. Thalassemia is also a hereditary autosomal global disease; globally, an estimated 270 million people suffer from or carry abnormal hemoglobin and thalassemia [1]. Generally, the clinical symptoms of thalassemia carriers are mild, or even indistinguishable from those of healthy individuals. However, if both couples are carriers of thalassemia, then each time the fetus is born, there is a 1/4 chance of developing thalassemia major. There is no effective cure for thalassemia major except for bone marrow transplantation. Therefore, in areas with a high prevalence of thalassemia, prenatal diagnosis is the most effective means and method to reduce the number of newborns with thalassemia major. Invasive prenatal diagnosis is a common method for the diagnosis of thalassemia at present. Invasive procedures include amniocentesis, chorionic villi sampling, or umbilical cord blood sampling, all of which are traumatic and can cause vaginal bleeding, cervical abnormalities, and an increased risk of fetal infection in pregnant women [2–4], and ultrasound-assisted sampling is needed.
An Expert Overview on Therapies in Non-Transfusion-Dependent Thalassemia: Classical to Cutting Edge in Treatment
Published in Hemoglobin, 2023
Mohammadreza Saeidnia, Pooria Fazeli, Arghavan Farzi, Maryam Atefy Nezhad, Mojtaba Shabani-Borujeni, Mehran Erfani, Gholamhossein Tamaddon, Mehran Karimi
Although the ‘thalassemia intermedia’ term does not have any molecular correlation and its diagnosis is partially clinical, there is a genotype/phenotype relationship. In the genetic aspect, β-TI is a heterogeneous disease that mostly occurs at a mutation point (deleted mutation is uncommon) in single/two alleles of the HBB gene loci on chromosome 11. Most of the patients with β-TI are homozygotes or compound heterozygotes. On the other hand, both β-globin loci are involved. As mentioned previously, the disease has a recessive genetic pattern. The β-TI phenotype may also result from an increase in α-globin chain synthesis through a triple or quadruple genotype with a β heterozygosity. The molecular basis of β-TI is heterogeneous. Generally, each inheritance or acquisitive parameter will reduce globin chain imbalance, thus it could produce milder clinical symptoms of the disease. Currently, three prime parameters have been identified: first, the existence of mild or off-ladder allele of β-thal; second, corresponding with α-thalassemia (α-thal); and third, inheritance, all of which are effective parameters in increasing γ chain synthesis that contribute to β-TI status. Generally, the definition of different forms of β-thal is based on disease severity and is not related to genetic abnormalities. Although clinical phenotypes of thalassemia minor are primarily different from β-TI, some similarities have been detected [3,6,10,11].
The population incidence of thalassemia gene variants in Baise, Guangxi, P. R. China, based on random samples
Published in Hematology, 2022
Bixiao Wei, Weijie Zhou, Mingkui Peng, Ju Long, Wangrong Wen
Thalassemia is a monogenic genetic disorder with a clear pathogenic mechanism, and genetic diagnosis and prenatal diagnosis are the main methods of prevention and control in regions with high prevalence[14]. A thalassemia three-level prevention and control strategy is widely implemented in the southern regions of China. For this, primary control facilities usually perform routine hematology tests and hemoglobin electrophoresis for subjects (fees of approximately $4 and $13 in 2022), and individuals with positive screening results are then tested for hot spot genetic variants by secondary testing laboratories (fees of approximately $80 in 2022). In regions with a high incidence of the thalassemia gene variant in the population, the government usually implements various exemption policies to increase the testing rate. Thanks to the effective implementation of the three-level prevention and control system, birth defects caused by thalassemia have decreased year by year[15].