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Infiltrative Cardiomyopathies
Published in Andreas P. Kalogeropoulos, Hal A. Skopicki, Javed Butler, Heart Failure, 2023
Arthur Qi, Quynh Nguyen, Haran Yogasundaram, Gavin Y. Oudit
The most common causes of acquired iron overload are transfusion-dependent anemias, such as thalassemia and sickle cell disease (Table 36.1). Thalassemia is characterized by a deficiency in the synthesis of one or more globin chains of haemoglobin.44 It is estimated that 1–5% of the world population are carriers of a mutant thalassemia allele; the disease is mostly prevalent in sub-Saharan Africa, the Mediterranean region, the Middle East, the Indian subcontinent, and East and Southeast Asia. Similarly, sickle cell disease, which results from mutations altering the β-globin chain of hemoglobin, is also known to be highly prevalent in Africa, India, the Mediterranean region, and the Middle East.45 With migration, sickle cell disease has been introduced to areas in which it was not historically endemic, such as northern Europe and North America. In addition to thalassemia and sickle cell anemia, other hematological conditions, such as myelodysplastic syndrome, sideroblastic anemia, acute myeloid leukemia, and congenital dyserythropoietic anemia, are all associated with secondary iron overload resulting from frequent blood transfusion.42,43 Additionally, iron overload has also been recognized in dialysis patients due to administration of erythropoiesis-stimulating agents and supplemental iron.46
Haematological Disease
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Genetic disorders of haemoglobin are caused by abnormalities of globin genes. A single abnormal allele, inherited from one parent, results in an asymptomatic heterozygous carrier state (a trait). If a person inherits abnormal alleles from both parents, they are affected (homozygous) and usually suffer from severe anaemia, together with other features arising from abnormal red cell structure and function.
Haematological disorders
Published in Judy Bothamley, Maureen Boyle, Medical Conditions Affecting Pregnancy and Childbirth, 2020
Haemoglobin is the essential element in red blood cells that carries oxygen from the lungs to the body’s tissues and returns carbon dioxide from the tissues back to the lungs. The globin part of haemoglobin is the part that is inherited and determines the characteristics of the haemoglobin. Globin is a protein consisting of two pairs of polypeptide chains, and its structure influences how easily the RBC stores and releases oxygen. Globin can contain several different types of polypeptide chains, termed alpha, beta, gamma and delta25.
Hb Santa Juana (β 108(G10) Asn > Ser): a low oxygen affinity hemoglobin variant in a family of Bosnian background
Published in Hematology, 2023
N. P. Wildenberg, C. Rossi, A. E. Kulozik, J. B. Kunz
Hemoglobin is a heterotetramer composed of two α- and two β-globin chains, with a total of four heme groups as oxygen binding sites. According to the allosteric two-state-model [2], the heterotetramer can exist in a relaxed R state with high oxygen affinity and a strained T state with low oxygen affinity. Binding of an oxygen molecule to one heme group increases the oxygen affinity of the other subunits. This effect explains the sigmoidal shape of the oxygen binding curve. Hemoglobin variants with decreased oxygen affinity stabilize the T-state and result in increased oxygen delivery to the tissues, while oxygen uptake in the lungs is decreased. The oxygen dissociation curve is right-shifted and characterized by a higher oxygen tension required to reach 50% saturation (p50). However, additional factors contribute to oxygen release into the tissue, such as the concentration of 2,3-bisphosphoglycerate, pH, and CO2 tension. Weak oxygen binding to hemoglobin favors oxygen release into the tissue, suppressing erythropoietin secretion and causing normocytic anemia. Although some patients expressing hemoglobin variants with decreased oxygen affinity present with cyanosis, most are asymptomatic. A low oxygen affinity hemoglobin variant may be suggested by otherwise unexplained reduced pulse oximetry measurements and normocytic anemia.
Effect of α+ Thalassemia on the Severity of Plasmodium falciparum Malaria in Different Sickle Cell Genotypes in Indian Adults: A Hospital-Based Study
Published in Hemoglobin, 2023
Prasanta Purohit, Pradeep Kumar Mohanty, Jogeswar Panigrahi, Kishalaya Das, Siris Patel
On the basis of the number of α-globin genes present, the cases were categorized into three genotypes. Normal α-globin genotype: cases with all four α-globin genes (αα/αα);Heterozygous α+-thalassemia: cases with three α-globin genes (−α/αα), which includes both the heterozygous −α3.7 (−α3.7/αα) and heterozygous −α4.2 (−α4.2/αα) deletions;Homozygous α+-thalassemia: cases with two α-globin genes (−α/−α), which includes the homozygous −α3.7 (−α3.7/−α3.7) deletions, homozygous −α4.2 (−α4.2/−α4.2) and double heterozygous state of both −α3.7 and −α4.2 (−α3.7/–α4.2) deletions
Overview of current progress and challenges in diagnosis, and management of pediatric sickle cell disease in Democratic Republic of the Congo
Published in Hematology, 2022
Emmanuel Tebandite Kasai, Jean Pierre Alworong’a Opara, Justin Ntokamunda Kadima, Masendu Kalenga, Salomon Batina Agasa, Roland Marini Djang’eing‘a, François Boemer
Hemoglobinopathy is defined as a blood pathology caused by genetic mutations that lead to qualitative and quantitative changes in structure and quantity of hemoglobin (Hb) chains [1]. To date, over a thousand variants of hemoglobin are described in the HbVar database. Not all these variants are clinically significant [2]. Globally, hemoglobinopathies fall into two main groups, including structural variants of hemoglobin (abnormal hemoglobins) and thalassemia syndromes (α-and β-thalassemia). Hemoglobin is a tetramer made up of two chains of α-globin and two chains of β-globin working together with heme to transport oxygen in the blood [1]. Normal adult hemoglobin (HbA) is referred to as αA2βA2 [1]. Variant hemoglobin is derived from genetic mutations in the structural genes of α-globin (HBA1 or HBA2) or β-globin (HBB) (exons).