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.Sickle Cell Trait: The condition of being heterozygous for hemoglobin S.Anemia: A reduction in the number of circulating ERYTHROCYTES or in the quantity of HEMOGLOBIN.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, Abnormal: Oxygen-carrying RED BLOOD CELLS in mammalian blood that are abnormal in structure or function.Antisickling Agents: Agents used to prevent or reverse the pathological events leading to sickling of erythrocytes in sickle cell 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.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.Anemia, Hemolytic: A condition of inadequate circulating red blood cells (ANEMIA) or insufficient HEMOGLOBIN due to premature destruction of red blood cells (ERYTHROCYTES).Anemia, Aplastic: A form of anemia in which the bone marrow fails to produce adequate numbers of peripheral blood elements.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.Fanconi Anemia: Congenital disorder affecting all bone marrow elements, resulting in ANEMIA; LEUKOPENIA; and THROMBOPENIA, and associated with cardiac, renal, and limb malformations as well as dermal pigmentary changes. Spontaneous CHROMOSOME BREAKAGE is a feature of this disease along with predisposition to LEUKEMIA. There are at least 7 complementation groups in Fanconi anemia: FANCA, FANCB, FANCC, FANCD1, FANCD2, FANCE, FANCF, FANCG, and FANCL. (from Online Mendelian Inheritance in Man, http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=227650, August 20, 2004)Hydroxyurea: An antineoplastic agent that inhibits DNA synthesis through the inhibition of ribonucleoside diphosphate reductase.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.Anemia, Hemolytic, Autoimmune: Acquired hemolytic anemia due to the presence of AUTOANTIBODIES which agglutinate or lyse the patient's own RED BLOOD CELLS.Anemia, Hypochromic: Anemia characterized by a decrease in the ratio of the weight of hemoglobin to the volume of the erythrocyte, i.e., the mean corpuscular hemoglobin concentration is less than normal. The individual cells contain less hemoglobin than they could have under optimal conditions. Hypochromic anemia may be caused by iron deficiency from a low iron intake, diminished iron absorption, or excessive iron loss. It can also be caused by infections or other diseases, therapeutic drugs, lead poisoning, and other conditions. (Stedman, 25th ed; from Miale, Laboratory Medicine: Hematology, 6th ed, p393)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.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Anemia, Macrocytic: Anemia characterized by larger than normal erythrocytes, increased mean corpuscular volume (MCV) and increased mean corpuscular hemoglobin (MCH).Anemia, Pernicious: A megaloblastic anemia occurring in children but more commonly in later life, characterized by histamine-fast achlorhydria, in which the laboratory and clinical manifestations are based on malabsorption of vitamin B 12 due to a failure of the gastric mucosa to secrete adequate and potent intrinsic factor. (Dorland, 27th ed)Hemoglobinopathies: A group of inherited disorders characterized by structural alterations within the hemoglobin molecule.Jamaica: An island in the Greater Antilles in the West Indies. Its capital is Kingston. It was discovered in 1494 by Columbus and was a Spanish colony 1509-1655 until captured by the English. Its flourishing slave trade was abolished in the 19th century. It was a British colony 1655-1958 and a territory of the West Indies Federation 1958-62. It achieved full independence in 1962. The name is from the Arawak Xaymaca, rich in springs or land of springs. (From Webster's New Geographical Dictionary, 1988, p564 & Room, Brewer's Dictionary of Names, 1992, p267)Acute Chest Syndrome: Respiratory syndrome characterized by the appearance of a new pulmonary infiltrate on chest x-ray, accompanied by symptoms of fever, cough, chest pain, tachypnea, or DYSPNEA, often seen in patients with SICKLE CELL ANEMIA. Multiple factors (e.g., infection, and pulmonary FAT EMBOLISM) may contribute to the development of the syndrome.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.Blood Transfusion: The introduction of whole blood or blood component directly into the blood stream. (Dorland, 27th ed)Hemoglobin C Disease: A disease characterized by compensated hemolysis with a normal hemoglobin level or a mild to moderate anemia. There may be intermittent abdominal discomfort, splenomegaly, and slight jaundice.Anemia, Sideroblastic: Anemia characterized by the presence of erythroblasts containing excessive deposits of iron in the marrow.Hemolysis: The destruction of ERYTHROCYTES by many different causal agents such as antibodies, bacteria, chemicals, temperature, and changes in tonicity.Hemoglobin A: Normal adult human hemoglobin. The globin moiety consists of two alpha and two beta chains.Anemia, Megaloblastic: A disorder characterized by the presence of ANEMIA, abnormally large red blood cells (megalocytes or macrocytes), and MEGALOBLASTS.Erythrocyte Count: The number of RED BLOOD CELLS per unit volume in a sample of venous BLOOD.Infectious Anemia Virus, Equine: A species of LENTIVIRUS, subgenus equine lentiviruses (LENTIVIRUSES, EQUINE), causing acute and chronic infection in horses. It is transmitted mechanically by biting flies, mosquitoes, and midges, and iatrogenically through unsterilized equipment. Chronic infection often consists of acute episodes with remissions.Anemia, Refractory: A severe sometimes chronic anemia, usually macrocytic in type, that does not respond to ordinary antianemic therapy.Anemia, Hemolytic, Congenital: Hemolytic anemia due to various intrinsic defects of the erythrocyte.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).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.Erythrocyte Deformability: Ability of ERYTHROCYTES to change shape as they pass through narrow spaces, such as the microvasculature.Hematocrit: The volume of packed RED BLOOD CELLS in a blood specimen. The volume is measured by centrifugation in a tube with graduated markings, or with automated blood cell counters. It is an indicator of erythrocyte status in disease. For example, ANEMIA shows a low value; POLYCYTHEMIA, a high value.Exchange Transfusion, Whole Blood: Repetitive withdrawal of small amounts of blood and replacement with donor blood until a large proportion of the blood volume has been exchanged. Used in treatment of fetal erythroblastosis, hepatic coma, sickle cell anemia, disseminated intravascular coagulation, septicemia, burns, thrombotic thrombopenic purpura, and fulminant malaria.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.Leg Ulcer: Ulceration of the skin and underlying structures of the lower extremity. About 90% of the cases are due to venous insufficiency (VARICOSE ULCER), 5% to arterial disease, and the remaining 5% to other causes.Globins: A superfamily of proteins containing the globin fold which is composed of 6-8 alpha helices arranged in a characterstic HEME enclosing structure.Pregnancy Complications, Hematologic: The co-occurrence of pregnancy and a blood disease (HEMATOLOGIC DISEASES) which involves BLOOD CELLS or COAGULATION FACTORS. The hematologic disease may precede or follow FERTILIZATION and it may or may not have a deleterious effect on the pregnant woman or FETUS.Erythrocyte Aging: The senescence of RED BLOOD CELLS. Lacking the organelles that make protein synthesis possible, the mature erythrocyte is incapable of self-repair, reproduction, and carrying out certain functions performed by other cells. This limits the average life span of an erythrocyte to 120 days.Erythropoietin: Glycoprotein hormone, secreted chiefly by the KIDNEY in the adult and the LIVER in the FETUS, that acts on erythroid stem cells of the BONE MARROW to stimulate proliferation and differentiation.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.Erythrocyte Transfusion: The transfer of erythrocytes from a donor to a recipient or reinfusion to the donor.Equine Infectious Anemia: Viral disease of horses caused by the equine infectious anemia virus (EIAV; INFECTIOUS ANEMIA VIRUS, EQUINE). It is characterized by intermittent fever, weakness, and anemia. Chronic infection consists of acute episodes with remissions.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.Pain: An unpleasant sensation induced by noxious stimuli which are detected by NERVE ENDINGS of NOCICEPTIVE NEURONS.Splenic Infarction: Insufficiency of arterial or venous blood supply to the spleen due to emboli, thrombi, vascular torsion, or pressure that produces a macroscopic area of necrosis. (From Stedman, 25th ed)Erythrocyte Membrane: The semi-permeable outer structure of a red blood cell. It is known as a red cell 'ghost' after HEMOLYSIS.Hemoglobinometry: Measurement of hemoglobin concentration in blood.Chicken anemia virus: The type species of GYROVIRUS, a small, non-enveloped DNA virus originally isolated from contaminated vaccines in Japan. It causes chicken infectious anemia and may possibly play a key role in hemorrhagic anemia syndrome, anemia dermatitis, and blue wing disease.Anemia, Dyserythropoietic, Congenital: A familial disorder characterized by ANEMIA with multinuclear ERYTHROBLASTS, karyorrhexis, asynchrony of nuclear and cytoplasmic maturation, and various nuclear abnormalities of bone marrow erythrocyte precursors (ERYTHROID PRECURSOR CELLS). Type II is the most common of the 3 types; it is often referred to as HEMPAS, based on the Hereditary Erythroblast Multinuclearity with Positive Acidified Serum test.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.Anemia, Diamond-Blackfan: A rare congenital hypoplastic anemia that usually presents early in infancy. The disease is characterized by a moderate to severe macrocytic anemia, occasional neutropenia or thrombocytosis, a normocellular bone marrow with erythroid hypoplasia, and an increased risk of developing leukemia. (Curr Opin Hematol 2000 Mar;7(2):85-94)Vascular Diseases: Pathological processes involving any of the BLOOD VESSELS in the cardiac or peripheral circulation. They include diseases of ARTERIES; VEINS; and rest of the vasculature system in the body.Blood Viscosity: The internal resistance of the BLOOD to shear forces. The in vitro measure of whole blood viscosity is of limited clinical utility because it bears little relationship to the actual viscosity within the circulation, but an increase in the viscosity of circulating blood can contribute to morbidity in patients suffering from disorders such as SICKLE CELL ANEMIA and POLYCYTHEMIA.Homozygote: An individual in which both alleles at a given locus are identical.Fanconi Anemia Complementation Group Proteins: A diverse group of proteins whose genetic MUTATIONS have been associated with the chromosomal instability syndrome FANCONI ANEMIA. Many of these proteins play important roles in protecting CELLS against OXIDATIVE STRESS.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)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.Oxygen: An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.Erythrocyte Aggregation: The formation of clumps of RED BLOOD CELLS under low or non-flow conditions, resulting from the attraction forces between the red blood cells. The cells adhere to each other in rouleaux aggregates. Slight mechanical force, such as occurs in the circulation, is enough to disperse these aggregates. Stronger or weaker than normal aggregation may result from a variety of effects in the ERYTHROCYTE MEMBRANE or in BLOOD PLASMA. The degree of aggregation is affected by ERYTHROCYTE DEFORMABILITY, erythrocyte membrane sialylation, masking of negative surface charge by plasma proteins, etc. BLOOD VISCOSITY and the ERYTHROCYTE SEDIMENTATION RATE are affected by the amount of erythrocyte aggregation and are parameters used to measure the aggregation.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.Nigeria: A republic in western Africa, south of NIGER between BENIN and CAMEROON. Its capital is Abuja.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.Oxyhemoglobins: A compound formed by the combination of hemoglobin and oxygen. It is a complex in which the oxygen is bound directly to the iron without causing a change from the ferrous to the ferric state.Hemorheology: The deformation and flow behavior of BLOOD and its elements i.e., PLASMA; ERYTHROCYTES; WHITE BLOOD CELLS; and BLOOD PLATELETS.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.Dimethyl Adipimidate: Bifunctional cross-linking agent that links covalently free amino groups of proteins or polypeptides, including those in cell membranes. It is used as reagent or fixative in immunohistochemistry and is a proposed antisickling agent.Anemia, Neonatal: The mildest form of erythroblastosis fetalis in which anemia is the chief manifestation.Prevalence: The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.Splenic DiseasesLutheran Blood-Group System: A complex blood group system having pairs of alternate antigens and amorphic genes, but also subject to a dominant independently segregating repressor.Hematinics: Agents which improve the quality of the blood, increasing the hemoglobin level and the number of erythrocytes. They are used in the treatment of anemias.Anemia, Refractory, with Excess of Blasts: Chronic refractory anemia with granulocytopenia, and/or thrombocytopenia. Myeloblasts and progranulocytes constitute 5 to 40 percent of the nucleated marrow cells.Kidney Papillary Necrosis: A complication of kidney diseases characterized by cell death involving KIDNEY PAPILLA in the KIDNEY MEDULLA. Damages to this area may hinder the kidney to concentrate urine resulting in POLYURIA. Sloughed off necrotic tissue may block KIDNEY PELVIS or URETER. Necrosis of multiple renal papillae can lead to KIDNEY FAILURE.Glucosephosphate Dehydrogenase Deficiency: A disease-producing enzyme deficiency subject to many variants, some of which cause a deficiency of GLUCOSE-6-PHOSPHATE DEHYDROGENASE activity in erythrocytes, leading to hemolytic anemia.Priapism: A prolonged painful erection that may lasts hours and is not associated with sexual activity. It is seen in patients with SICKLE CELL ANEMIA, advanced malignancy, spinal trauma; and certain drug treatments.Blood Cell Count: The number of LEUKOCYTES and ERYTHROCYTES per unit volume in a sample of venous BLOOD. A complete blood count (CBC) also includes measurement of the HEMOGLOBIN; HEMATOCRIT; and ERYTHROCYTE INDICES.Erythrocyte Inclusions: Pathologic inclusions occurring in erythrocytes.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.2,3-Diphosphoglycerate: A highly anionic organic phosphate which is present in human red blood cells at about the same molar ratio as hemoglobin. It binds to deoxyhemoglobin but not the oxygenated form, therefore diminishing the oxygen affinity of hemoglobin. This is essential in enabling hemoglobin to unload oxygen in tissue capillaries. It is also an intermediate in the conversion of 3-phosphoglycerate to 2-phosphoglycerate by phosphoglycerate mutase (EC 126.96.36.199). (From Stryer Biochemistry, 4th ed, p160; Enzyme Nomenclature, 1992, p508)Neonatal Screening: The identification of selected parameters in newborn infants by various tests, examinations, or other procedures. Screening may be performed by clinical or laboratory measures. A screening test is designed to sort out healthy neonates (INFANT, NEWBORN) from those not well, but the screening test is not intended as a diagnostic device, rather instead as epidemiologic.Fanconi Anemia Complementation Group C Protein: A Fanconi anemia complementation group protein that regulates the activities of CYTOCHROME P450 REDUCTASE and GLUTATHIONE S-TRANSFERASE. It is found predominately in the CYTOPLASM, but moves to the CELL NUCLEUS in response to FANCE PROTEIN.Fanconi Anemia Complementation Group D2 Protein: A Fanconi anemia complementation group protein that undergoes mono-ubiquitination by FANCL PROTEIN in response to DNA DAMAGE. Also, in response to IONIZING RADIATION it can undergo PHOSPHORYLATION by ataxia telangiectasia mutated protein. Modified FANCD2 interacts with BRCA2 PROTEIN in a stable complex with CHROMATIN, and it is involved in DNA REPAIR by homologous RECOMBINATION.Retinal DiseasesFanconi Anemia Complementation Group A Protein: A Fanconi anemia complementation group protein that is the most commonly mutated protein in FANCONI ANEMIA. It undergoes PHOSPHORYLATION by PROTEIN KINASE B and forms a complex with FANCC PROTEIN in the CELL NUCLEUS.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.Hyphema: Bleeding in the anterior chamber of the eye.Splenectomy: Surgical procedure involving either partial or entire removal of the spleen.Infant, Newborn: An infant during the first month after birth.Hypertension, Pulmonary: Increased VASCULAR RESISTANCE in the PULMONARY CIRCULATION, usually secondary to HEART DISEASES or LUNG DISEASES.Premarital Examinations: Medical tests taken by couples planning to be married in order to determine presence of genetic and contagious diseases.Heinz Bodies: Abnormal intracellular inclusions, composed of denatured hemoglobin, found on the membrane of red blood cells. They are seen in thalassemias, enzymopathies, hemoglobinopathies, and after splenectomy.Splenomegaly: Enlargement of the spleen.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.MethemoglobinDiphosphoglyceric AcidsEnuresis: Involuntary discharge of URINE after expected age of completed development of urinary control. This can happen during the daytime (DIURNAL ENURESIS) while one is awake or during sleep (NOCTURNAL ENURESIS). Enuresis can be in children or in adults (as persistent primary enuresis and secondary adult-onset enuresis).Mediterranean Islands: Scattered islands in the Mediterranean Sea. The chief islands are the Balearic Islands (belong to Spain; Majorca and Minorca are among these), Corsica (belongs to France), Crete (belongs to Greece), CYPRUS (a republic), the Cyclades, Dodecanese and Ionian Islands (belong to Greece), MALTA (a republic), Sardinia and SICILY (belong to Italy). (From Webster's New Geographical Dictionary, 1988, p747)Spherocytosis, Hereditary: A group of familial congenital hemolytic anemias characterized by numerous abnormally shaped erythrocytes which are generally spheroidal. The erythrocytes have increased osmotic fragility and are abnormally permeable to sodium ions.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Anemia, Hemolytic, Congenital Nonspherocytic: Any one of a group of congenital hemolytic anemias in which there is no abnormal hemoglobin or spherocytosis and in which there is a defect of glycolysis in the erythrocyte. Common causes include deficiencies in GLUCOSE-6-PHOSPHATE ISOMERASE; PYRUVATE KINASE; and GLUCOSE-6-PHOSPHATE DEHYDROGENASE.Pallor: A clinical manifestation consisting of an unnatural paleness of the skin.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Hematologic Tests: Tests used in the analysis of the hemic system.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.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Tricuspid Valve Insufficiency: Backflow of blood from the RIGHT VENTRICLE into the RIGHT ATRIUM due to imperfect closure of the TRICUSPID VALVE.