beta-Thalassemia: A disorder characterized by reduced synthesis of the beta chains of hemoglobin. There is retardation of hemoglobin A synthesis in the heterozygous form (thalassemia minor), which is asymptomatic, while in the homozygous form (thalassemia major, Cooley's anemia, Mediterranean anemia, erythroblastic anemia), which can result in severe complications and even death, hemoglobin A synthesis is absent.Thalassemia: A group of hereditary hemolytic anemias in which there is decreased synthesis of one or more hemoglobin polypeptide chains. There are several genetic types with clinical pictures ranging from barely detectable hematologic abnormality to severe and fatal anemia.Hemoglobin E: An abnormal hemoglobin that results from the substitution of lysine for glutamic acid at position 26 of the beta chain. It is most frequently observed in southeast Asian populations.Globins: A superfamily of proteins containing the globin fold which is composed of 6-8 alpha helices arranged in a characterstic HEME enclosing structure.Hemoglobin A2: An adult hemoglobin component normally present in hemolysates from human erythrocytes in concentrations of about 3%. The hemoglobin is composed of two alpha chains and two delta chains. The percentage of HbA2 varies in some hematologic disorders, but is about double in beta-thalassemia.beta-Globins: Members of the beta-globin family. In humans, they are encoded in a gene cluster on CHROMOSOME 11. They include epsilon-globin, gamma-globin, delta-globin and beta-globin. There is also a pseudogene of beta (theta-beta) in the gene cluster. Adult HEMOGLOBIN is comprised of two ALPHA-GLOBIN chains and two beta-globin chains.Fetal Hemoglobin: The major component of hemoglobin in the fetus. This HEMOGLOBIN has two alpha and two gamma polypeptide subunits in comparison to normal adult hemoglobin, which has two alpha and two beta polypeptide subunits. Fetal hemoglobin concentrations can be elevated (usually above 0.5%) in children and adults affected by LEUKEMIA and several types of ANEMIA.Hemoglobinopathies: A group of inherited disorders characterized by structural alterations within the hemoglobin molecule.Hemoglobins, Abnormal: Hemoglobins characterized by structural alterations within the molecule. The alteration can be either absence, addition or substitution of one or more amino acids in the globin part of the molecule at selected positions in the polypeptide chains.Iron Overload: An excessive accumulation of iron in the body due to a greater than normal absorption of iron from the gastrointestinal tract or from parenteral injection. This may arise from idiopathic hemochromatosis, excessive iron intake, chronic alcoholism, certain types of refractory anemia, or transfusional hemosiderosis. (From Churchill's Illustrated Medical Dictionary, 1989)alpha-Thalassemia: A disorder characterized by reduced synthesis of the alpha chains of hemoglobin. The severity of this condition can vary from mild anemia to death, depending on the number of genes deleted.Chelation Therapy: Therapy of heavy metal poisoning using agents which sequester the metal from organs or tissues and bind it firmly within the ring structure of a new compound which can be eliminated from the body.alpha-Globins: Members of the alpha-globin family. In humans, they are encoded in a gene cluster on CHROMOSOME 16. They include zeta-globin and alpha-globin. There are also pseudogenes of zeta (theta-zeta) and alpha (theta-alpha) in the cluster. Adult HEMOGLOBIN is comprised of 2 alpha-globin chains and 2 beta-globin chains.Iron Chelating Agents: Organic chemicals that form two or more coordination links with an iron ion. Once coordination has occurred, the complex formed is called a chelate. The iron-binding porphyrin group of hemoglobin is an example of a metal chelate found in biological systems.Heterozygote: An individual having different alleles at one or more loci regarding a specific character.gamma-Globins: Members of the beta-globin family. In humans, two non-allelic types of gamma-globin - A gamma and G gamma are encoded in the beta-globin gene cluster on CHROMOSOME 11. Two gamma-globin chains combine with two ZETA-GLOBIN chains to form the embryonic hemoglobin Portland. Fetal HEMOGLOBIN F is formed from two gamma-globin chains combined with two ALPHA-GLOBIN chains.Hemoglobinuria: The presence of free HEMOGLOBIN in the URINE, indicating hemolysis of ERYTHROCYTES within the vascular system. After saturating the hemoglobin-binding proteins (HAPTOGLOBINS), free hemoglobin begins to appear in the urine.Erythropoiesis: The production of red blood cells (ERYTHROCYTES). In humans, erythrocytes are produced by the YOLK SAC in the first trimester; by the liver in the second trimester; by the BONE MARROW in the third trimester and after birth. In normal individuals, the erythrocyte count in the peripheral blood remains relatively constant implying a balance between the rate of erythrocyte production and rate of destruction.Prenatal Diagnosis: Determination of the nature of a pathological condition or disease in the postimplantation EMBRYO; FETUS; or pregnant female before birth.Hemoglobin A: Normal adult human hemoglobin. The globin moiety consists of two alpha and two beta chains.Blood Transfusion: The introduction of whole blood or blood component directly into the blood stream. (Dorland, 27th ed)Erythroid Precursor Cells: The cells in the erythroid series derived from MYELOID PROGENITOR CELLS or from the bi-potential MEGAKARYOCYTE-ERYTHROID PROGENITOR CELLS which eventually give rise to mature RED BLOOD CELLS. The erythroid progenitor cells develop in two phases: erythroid burst-forming units (BFU-E) followed by erythroid colony-forming units (CFU-E); BFU-E differentiate into CFU-E on stimulation by ERYTHROPOIETIN, and then further differentiate into ERYTHROBLASTS when stimulated by other factors.Anemia, Sickle Cell: A disease characterized by chronic hemolytic anemia, episodic painful crises, and pathologic involvement of many organs. It is the clinical expression of homozygosity for hemoglobin S.Deferoxamine: Natural product isolated from Streptomyces pilosus. It forms iron complexes and is used as a chelating agent, particularly in the mesylate form.Hemoglobins: The oxygen-carrying proteins of ERYTHROCYTES. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements.Hemoglobin C: A commonly occurring abnormal hemoglobin in which lysine replaces a glutamic acid residue at the sixth position of the beta chains. It results in reduced plasticity of erythrocytes.Homozygote: An individual in which both alleles at a given locus are identical.Hepcidins: Forms of hepcidin, a cationic amphipathic peptide synthesized in the liver as a prepropeptide which is first processed into prohepcidin and then into the biologically active hepcidin forms, including in human the 20-, 22-, and 25-amino acid residue peptide forms. Hepcidin acts as a homeostatic regulators of iron metabolism and also possesses antimicrobial activity.delta-Globins: A member of the beta-globin family. In humans, delta-globin is encoded in the beta-globin gene cluster located on CHROMOSOME 11. Two delta-globin chains along with two alpha-globin chains form HEMOGLOBIN A2 which makes up about 3% of the HEMOGLOBIN in adults.Erythrocyte Count: The number of RED BLOOD CELLS per unit volume in a sample of venous BLOOD.Heterozygote Detection: Identification of genetic carriers for a given trait.Hemoglobin H: An abnormal hemoglobin composed of four beta chains. It is caused by the reduced synthesis of the alpha chain. This abnormality results in ALPHA-THALASSEMIA.Ferritins: Iron-containing proteins that are widely distributed in animals, plants, and microorganisms. Their major function is to store IRON in a nontoxic bioavailable form. Each ferritin molecule consists of ferric iron in a hollow protein shell (APOFERRITINS) made of 24 subunits of various sequences depending on the species and tissue types.Premarital Examinations: Medical tests taken by couples planning to be married in order to determine presence of genetic and contagious diseases.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Lentivirus: A genus of the family RETROVIRIDAE consisting of non-oncogenic retroviruses that produce multi-organ diseases characterized by long incubation periods and persistent infection. Lentiviruses are unique in that they contain open reading frames (ORFs) between the pol and env genes and in the 3' env region. Five serogroups are recognized, reflecting the mammalian hosts with which they are associated. HIV-1 is the type species.Reticulocytes: Immature ERYTHROCYTES. In humans, these are ERYTHROID CELLS that have just undergone extrusion of their CELL NUCLEUS. They still contain some organelles that gradually decrease in number as the cells mature. RIBOSOMES are last to disappear. Certain staining techniques cause components of the ribosomes to precipitate into characteristic "reticulum" (not the same as the ENDOPLASMIC RETICULUM), hence the name reticulocytes.Hemoglobin, Sickle: An abnormal hemoglobin resulting from the substitution of valine for glutamic acid at position 6 of the beta chain of the globin moiety. The heterozygous state results in sickle cell trait, the homozygous in sickle cell anemia.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Iron: A metallic element with atomic symbol Fe, atomic number 26, and atomic weight 55.85. It is an essential constituent of HEMOGLOBINS; CYTOCHROMES; and IRON-BINDING PROTEINS. It plays a role in cellular redox reactions and in the transport of OXYGEN.Reticulocyte Count: The number of RETICULOCYTES per unit volume of BLOOD. The values are expressed as a percentage of the ERYTHROCYTE COUNT or in the form of an index ("corrected reticulocyte index"), which attempts to account for the number of circulating erythrocytes.Erythrocytes, Abnormal: Oxygen-carrying RED BLOOD CELLS in mammalian blood that are abnormal in structure or function.Hematopoiesis, Extramedullary: The formation and development of blood cells outside the BONE MARROW, as in the SPLEEN; LIVER; or LYMPH NODES.Siderosis: A form of pneumoconiosis resulting from inhalation of iron in the mining dust or welding fumes.Beta-Globulins: Serum proteins with an electrophoretic mobility that falls between ALPHA-GLOBULINS and GAMMA-GLOBULINS.Splenectomy: Surgical procedure involving either partial or entire removal of the spleen.Pyridones: Pyridine derivatives with one or more keto groups on the ring.Benzoates: Derivatives of BENZOIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the carboxybenzene structure.ItalyMetal Metabolism, Inborn ErrorsAbortion, Eugenic: Abortion performed because of possible fetal defects.Erythrocyte Deformability: Ability of ERYTHROCYTES to change shape as they pass through narrow spaces, such as the microvasculature.SicilyErythroid Cells: The series of cells in the red blood cell lineage at various stages of differentiation.Antimicrobial Cationic Peptides: Small cationic peptides that are an important component, in most species, of early innate and induced defenses against invading microbes. In animals they are found on mucosal surfaces, within phagocytic granules, and on the surface of the body. They are also found in insects and plants. Among others, this group includes the DEFENSINS, protegrins, tachyplesins, and thionins. They displace DIVALENT CATIONS from phosphate groups of MEMBRANE LIPIDS leading to disruption of the membrane.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Erythrocyte Indices: ERYTHROCYTE size and HEMOGLOBIN content or concentration, usually derived from ERYTHROCYTE COUNT; BLOOD hemoglobin concentration; and HEMATOCRIT. The indices include the mean corpuscular volume (MCV), the mean corpuscular hemoglobin (MCH), and the mean corpuscular hemoglobin concentration (MCHC).Osmotic Fragility: RED BLOOD CELL sensitivity to change in OSMOTIC PRESSURE. When exposed to a hypotonic concentration of sodium in a solution, red cells take in more water, swell until the capacity of the cell membrane is exceeded, and burst.Genetic Counseling: An educational process that provides information and advice to individuals or families about a genetic condition that may affect them. The purpose is to help individuals make informed decisions about marriage, reproduction, and other health management issues based on information about the genetic disease, the available diagnostic tests, and management programs. Psychosocial support is usually offered.Erythroblasts: Immature, nucleated ERYTHROCYTES occupying the stage of ERYTHROPOIESIS that follows formation of ERYTHROID PRECURSOR CELLS and precedes formation of RETICULOCYTES. The normal series is called normoblasts. Cells called MEGALOBLASTS are a pathologic series of erythroblasts.Erythrocyte Inclusions: Pathologic inclusions occurring in erythrocytes.Pedigree: The record of descent or ancestry, particularly of a particular condition or trait, indicating individual family members, their relationships, and their status with respect to the trait or condition.Hemoglobin Subunits: The PROTEIN SUBUNITS that comprise multimeric HEMOGLOBINS.Hydroxyurea: An antineoplastic agent that inhibits DNA synthesis through the inhibition of ribonucleoside diphosphate reductase.Chromosome Deletion: Actual loss of portion of a chromosome.Erythrocyte Membrane: The semi-permeable outer structure of a red blood cell. It is known as a red cell 'ghost' after HEMOLYSIS.Amniocentesis: Percutaneous transabdominal puncture of the uterus during pregnancy to obtain amniotic fluid. It is commonly used for fetal karyotype determination in order to diagnose abnormal fetal conditions.Hemoglobin SC Disease: One of the sickle cell disorders characterized by the presence of both hemoglobin S and hemoglobin C. It is similar to, but less severe than sickle cell anemia.Genes: A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.Genetic Therapy: Techniques and strategies which include the use of coding sequences and other conventional or radical means to transform or modify cells for the purpose of treating or reversing disease conditions.Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Human Migration: Periodic movement of human settlement from one geographical location to another.Pyuria: The presence of white blood cells (LEUKOCYTES) in the urine. It is often associated with bacterial infections of the urinary tract. Pyuria without BACTERIURIA can be caused by TUBERCULOSIS, stones, or cancer.Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.Iron Compounds: Organic and inorganic compounds that contain iron as an integral part of the molecule.Asia, Southeastern: The geographical area of Asia comprising BORNEO; BRUNEI; CAMBODIA; INDONESIA; LAOS; MALAYSIA; the MEKONG VALLEY; MYANMAR (formerly Burma), the PHILIPPINES; SINGAPORE; THAILAND; and VIETNAM.DNA Mutational Analysis: Biochemical identification of mutational changes in a nucleotide sequence.Hemosiderosis: Conditions in which there is a generalized increase in the iron stores of body tissues, particularly of liver and the MONONUCLEAR PHAGOCYTE SYSTEM, without demonstrable tissue damage. The name refers to the presence of stainable iron in the tissue in the form of hemosiderin.Chorionic Villi Sampling: A method for diagnosis of fetal diseases by sampling the cells of the placental chorionic villi for DNA analysis, presence of bacteria, concentration of metabolites, etc. The advantage over amniocentesis is that the procedure can be carried out in the first trimester.