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Sickle cell anemia, sickle cell beta-thalassemia, and thalassemia major in Albania: characterization of mutations.

We have analyzed the hemoglobin abnormalities in nearly 50 Albanian patients with a significant hemoglobinopathy and included 37 relatives in this study. Sickle cell anemia (SS) is a common disorder; all 15 sickle cell anemia patients had the complications expected for this disease. The beta S haplotype was type 19 (Benin); alpha-thalassemia-2 was rare. Three beta-thalassemia alleles (IVS-I-110, G-->A; codon 39, C-->T; IVS-I-6, T-->C) were present in nearly 85% of the beta-thalassemia alleles; their frequencies were intermediate between those observed in the populations of neighboring countries. A few rare mutations were also found, which might have originated in India, Turkey, Macedonia, and Greece. Nearly all patients with Hb S-beta-thalassemia had the IVS-I-110 (G-->A) mutation. The frequencies of 11 beta-thalassemia mutations in 17 mostly Mediterranean countries have been reviewed.

Adolescent↗

Genetic modulation of sickle cell anemia.

Sickle cell anemia, a common disorder associated with reduced life span of the red blood cell and vasoocclusive events, is caused by a mutation in the beta-hemoglobin gene. Yet, despite this genetic homogeneity, the phenotype of the disease is heterogeneous. This suggests the modulating influence of associated inherited traits. Some of these may influence the accumulation of fetal hemoglobin, a hemoglobin type that interferes with the polymerization of sickle hemoglobin. Another inherited trait determines the accumulation of alpha-globin chains. This review focuses on potential genetic regulators of the phenotype of sickle cell anemia.

Anemia, Sickle Cell↗

[Sickle cell anemia].

Sickle cell anemia is a disease having both hemolytic anemia and vasocclusive phenomenon. The mutant gene product (hemoglobin S[HbS], beta 6glu-->val) has the tendency to polymerize at low oxygen tension and cause the sickling phenomenon. This has been assumed to be the dominant factor of the pathophysiology in the sickle cell anemia. In addition, unstable HbS, disturbed cation homeostasis and adhesiveness of sickle cell to the endothelium are sufficient to impact on clinical features. The unstable HbS generates oxidant, induces iron decompartmentalization and cellular dehydration, resulting in abnormal microrheology, endothelial adhesivity, phospholipids destabilization and protein defects. These membrane defects and HbS polymerization (RBC sickling) play the important role on the pathophysiology (hemolytic anemia and vasocclusion) in sickle cell anemia.

Anemia, Sickle Cell↗

Fourier analysis reveals increased trabecular spacing in sickle cell anemia.

Sickle cell anemia may expand marrow spaces in the jaws. Fourier analysis is well-suited to the analysis of trabecular spacing in radiographs. We hypothesize that individuals with sickle cell anemia demonstrate increased intertrabecular spacing. Periapical radiographs of 18 African Americans with sickle cell disease and 18 controls were examined by one-dimensional discrete Fourier analyses in both jaws for measurement of the spatial frequency distribution of repeating trabecular structures. A strut analysis of trabeculae was also performed and the results compared. Trabecular structures in individuals with sickle cell anemia revealed increased intertrabecular distance compared with controls. Strut analysis revealed significant reductions in trabecular complexity. Fourier analysis allows for the classification of subjects with 94% sensitivity and specificity. Fourier analysis of dental radiographs is a more effective method of identifying individuals with sickle cell anemia than strut analysis.

Adult↗

Dental management of patients with sickle cell anemia.

Sickle cell anemia is endemic in certain parts of the world. With the increase in immigration into Canada from some of these areas, new demands are being placed on the country's health care system. However, improved methods of managing sickle cell anemia have resulted in a longer lifespan and better quality of life for patients afflicted with the disease. In most cases, these individuals can now remain out in the community for most of their lives, and are therefore likely to seek treatment from a neighborhood dentist. Consequently, dentists need to have an appreciation of sickle cell anemia and its implications for dental health. This article outlines the physiology, medical aspects, and dental manifestations of sickle cell anemia, and gives guidelines for its dental management.

Anemia, Sickle Cell↗

The pain experience of patients with sickle cell anemia.

Sickle cell anemia is a genetic disorder that affects 1 in 600 black infants in the United States. The painful crisis is one of its most characteristic manifestations and consists of pain in the extremities, back, abdomen, or chest. It may occur in 4 phases and may be precipitated by a variety of factors. The frequency, location, duration, severity, and character of pain differ both within and among patients. The pain may be localized, involve several areas, be diffuse, or be migratory. The intensity of pain varies from mild to excruciating and is perceived to be more intense by those who have experienced other forms of pain such as postoperative pain. Patients with sickle cell anemia who experience frequent painful crises exhibit problems with self-concept and low self-esteem, anxiety, depression, dissatisfaction with body image, poor school performance, social isolation, decreased participation in normal activities of daily living, and poor peer and family relationships. The periodic and unpredictable episodes can be incapacitating and may affect the way children see and feel about themselves, the way they relate to other people, the goals they set for themselves, and the way they approach a range of activities and situations. Research is very limited, and most of the available literature is based on personal observations, opinions, and anecdotal reports. The purpose of this report is to describe the phases of a painful episode as well as to examine the predisposing factors to, defining characteristics of, and patient outcomes associated with a painful crisis from sickle cell anemia.

Activities of Daily Living↗

The heart in sickle cell anemia.

Sickle cell anemia is a lifelong debilitating disease often required multiple, frequent hospital admissions. Multiple organ systems become damaged, but the heart, although demonstrating abnormalities, is relatively spared. With increasing life span of these patients, cardiac dysfunction may become more prominent. Recent noninvasive and pathologic studies have given new information on the effect of this disease on the heart. This article reviews the current knowledge of cardiac involvement in sickle cell anemia.

Adolescent↗

Pleiotropic and epistatic effects in sickle cell anemia.

Sickle cell anemia is the first monogenic disease ever described, and it became the paradigm for a disease traceable to a single mutation in a single gene. Pauling's concept of "molecular disease," based on this discovery, opened a new chapter in the history of medicine. Nevertheless, at the phenotypic level, sickle cell anemia is not a monogenic disease; it is a multigenic disease. The latter is the product of pleiotropic genes (involved in secondary pathophysiologic events) and epistatic genes (same gene but with significant pathophysiologic consequences among individual=polymorphism). These secondary events are an important part of the phenotype and explain the intense interindividual differences in the severity of the disease, in spite of all the patients having the same sickle globin gene in the homozygote form. In the last decade a number of epistatic genes and pleiotropic genes have been defined, and many others are potential candidates. CHIP technology and high-throughput sequencing promise to accelerate our full multigenic understanding of this disease, contributing to a more individualized concept of disease in conjunction as we enter the new millennium.

Anemia, Sickle Cell↗

Effects of mixed hematopoietic chimerism in a mouse model of bone marrow transplantation for sickle cell anemia.

Sickle cell anemia (SCA) is an inherited disorder of beta-globin, resulting in red blood cell rigidity, anemia, painful crises, organ infarctions, and reduced life expectancy. Allogeneic blood or marrow transplantation (BMT) can cure SCA but is associated with an 8% to 10% mortality rate, primarily from complications of marrow-ablative conditioning. Transplantation of allogeneic marrow after less intensive conditioning reduces toxicity but may result in stable mixed hematopoietic chimerism. The few SCA patients who inadvertently developed mixed chimerism after BMT remain symptom free, suggesting that mixed chimerism can reduce disease-related morbidity. However, because the effects of various levels of mixed chimerism on organ pathology have not been characterized, this study examined the histologic effects of an increasing percentage of normal donor hematopoiesis in a mouse model of BMT for SCA. In lethally irradiated normal mice that were reconstituted with varying ratios of T-cell-depleted marrow from normal and transgenic "sickle cell" mice, normal myeloid chimerism in excess of 25% was associated with more than 90% normal hemoglobin (Hb). However, 70% normal myeloid chimerism was required to reverse the anemia. Organ pathology, including liver infarction, was present in mice with sickle Hb (HbS) levels as low as 16.8% (19.6% normal myeloid chimerism). Histologic abnormalities increased in severity up to 80% HbS, but were less severe in mice with more than 80% HbS than in those with 40% to 80% HbS. Therefore, stable mixed chimerism resulting from nonmyeloablative BMT may reduce the morbidity from SCA, but prevention of all disease complications may require minimizing the fraction of circulating sickle red cells. (Blood. 2001;97:3960-3965)

Anemia, Sickle Cell↗

Transgenic knockout mice exclusively expressing human hemoglobin S after transfer of a 240-kb betas-globin yeast artificial chromosome: A mouse model of sickle cell anemia.

Sickle cell anemia (SCA) and thalassemia are among the most common genetic diseases worldwide. Current approaches to the development of murine models of SCA involve the elimination of functional murine alpha- and beta-globin genes and substitution with human alpha and betas transgenes. Recently, two groups have produced mice that exclusively express human HbS. The transgenic lines used in these studies were produced by coinjection of human alpha-, gamma-, and beta-globin constructs. Thus, all of the transgenes are integrated at a single chromosomal site. Studies in transgenic mice have demonstrated that the normal gene order and spatial organization of the members of the human beta-globin gene family are required for appropriate developmental and stage-restricted expression of the genes. As the cis-acting sequences that participate in activation and silencing of the gamma- and beta-globin genes are not fully defined, murine models that preserve the normal structure of the locus are likely to have significant advantages for validating future therapies for SCA. To produce a model of SCA that recapitulates not only the phenotype, but also the genotype of patients with SCA, we have generated mice that exclusively express HbS after transfer of a 240-kb betas yeast artificial chromosome. These mice have hemolytic anemia, 10% irreversibly sickled cells in their peripheral blood, reticulocytosis, and other phenotypic features of SCA.

Anemia, Sickle Cell↗

Sickle cell anemia.

Sickle cell anemia (SCA) is a disease caused by production of abnormal hemoglobin, which binds with other abnormal hemoglobin molecules within the red blood cell to cause rigid deformation of the cell. This deformation impairs the ability of the cell to pass through small vascular channels; sludging and congestion of vascular beds may result, followed by tissue ischemia and infarction. Infarction is common throughout the body in the patient with SCA, and it is responsible for the earliest clinical manifestation, the acute pain crisis, which is thought to result from marrow infarction. Over time, such insults result in medullary bone infarcts and epiphyseal osteonecrosis. In the brain, white matter and gray matter infarcts are seen, causing cognitive impairment and functional neurologic deficits. The lungs are also commonly affected, with infarcts, emboli (from marrow infarcts and fat necrosis), and a markedly increased propensity for pneumonia. The liver, spleen, and kidney may experience infarction as well. An unusual but life-threatening complication of SCA is sequestration syndrome, wherein a considerable amount of the intravascular volume is sequestered in an organ (usually the spleen), causing vascular collapse; its pathogenesis is unknown. Finally, because the red blood cells are abnormal, they are removed from the circulation, resulting in a hemolytic anemia. For the patient with SCA, however, the ischemic complications of the disease far outweigh the anemia in clinical importance.

Anemia, Sickle Cell↗

Modulation of the phenotypic diversity of sickle cell anemia.

Sickle cell anemia is noted for being phenotypically heterogeneous. This suggests that there are genetic influences that moderate the effects of the sickle hemoglobin mutation. In this review I focus on genetically determined modulation of hemoglobin concentration and fetal hemoglobin levels. Each of these variables has important influences upon sickle hemoglobin polymerization and the resulting pathophysiology.

Anemia, Sickle Cell↗

Pseudomoyamoya in sickle cell anemia.

Sickle cell (drepanocytic) anemia is a hereditary blood disease occurring very rarely in Mexico. A 13-year-old Mexican boy with sickle cell anemia eventually died of a cerebrovascular accident of the brain stem, as shown by computerized tomography (CT). A characteristic moyamoya-like angiographic pattern was demonstrated on bilateral carotid and left vertebral arteriograms. Moyamoya disease has no known etiology, but the characteristic angiographic features of moyamoya have been observed in conjunction with some other disease of known origin (including sickle cell anemia). It is therefore my belief that these latter cases should be referred to as pseudomoyamoya and not true moyamoya.

Adolescent↗

Principles of blood transfusion in sickle cell anemia.

Sickle cell anemia (SCA) is one of the commonly inherited hemoglobinopathies in the Kingdom of Saudi Arabia. It is characterized by periods of remissions and exacerbations called crises as well as certain pathological phenomenon such as acute chest syndrome, priapism, hepatopathy, and cerebrovascular stroke. Blood transfusion (BT) as therapy and prophylaxis in SCA, although was advocated as early as the 1940's, there are still debates regarding its benefits and risks. This is a review of the value of BT in patients with SCA with emphasis on the risks and benefits as well as guidelines towards safe BT.

Anemia, Sickle Cell↗

Prognostic significance of early vaso-occlusive complications in children with sickle cell anemia.

Sickle cell anemia (SS) is highly phenotypically variable, and early predictors of outcome could guide clinical care. To determine whether early vaso-occlusive complications predicted subsequent adverse outcomes in the Dallas Newborn Cohort, we studied all members with SS or sickle-beta0-thalassemia who presented in their first year of life and had 5 years or more of follow-up. We defined 3 potential early predictors: hospitalizations in the first 3 years of life for (1) painful events other than dactylitis, (2) dactylitis, and (3) acute chest syndrome (ACS). We studied the associations of these predictors with the following late adverse outcomes (occurring after the third birthday): death, first overt stroke, use of disease-modifying therapy, and hospitalizations for pain events and ACS. None of the early events predicted death or stroke. Early pain and ACS both predicted a modest, temporary increase in the number of later painful episodes, but early ACS strongly increased the odds of more frequent ACS throughout childhood. Dactylitis had limited utility as a predictor. Although we still lack a useful prognostic framework for young children with SS, those who experience early ACS might be candidates for higher risk interventions to mitigate or cure their disease.

Acute Disease↗

Genetic dissection and prognostic modeling of overt stroke in sickle cell anemia.

Sickle cell anemia (SCA) is a paradigmatic single gene disorder caused by homozygosity with respect to a unique mutation at the beta-globin locus. SCA is phenotypically complex, with different clinical courses ranging from early childhood mortality to a virtually unrecognized condition. Overt stroke is a severe complication affecting 6-8% of individuals with SCA. Modifier genes might interact to determine the susceptibility to stroke, but such genes have not yet been identified. Using Bayesian networks, we analyzed 108 SNPs in 39 candidate genes in 1,398 individuals with SCA. We found that 31 SNPs in 12 genes interact with fetal hemoglobin to modulate the risk of stroke. This network of interactions includes three genes in the TGF-beta pathway and SELP, which is associated with stroke in the general population. We validated this model in a different population by predicting the occurrence of stroke in 114 individuals with 98.2% accuracy.

Anemia, Sickle Cell↗

Sickle cell heart disease. Two-dimensional echo and Doppler ultrasonographic findings in the hearts of adult patients with sickle cell anemia.

Sickle cell anemia (SCA) is a commonly diagnosed condition in the black population in the United States. With better medical management, patients with SCA are living longer and what were previously uncommon sequelae are being recognized frequently, including those involving the cardiovascular system. Previous reports on the cardiovascular effects of SCA have focused predominantly on children, but the conclusions remain controversial. To study this question further, 40 adult patients with documented SCA were examined using two-dimensional and Doppler cardiac ultrasound. Valvular structures were normal despite an increased incidence of flow murmurs. Abnormalities were found more frequently in the left heart than the right, as manifested primarily by increased left ventricular mass, and left ventricular and left atrial dilatation with preservation of systolic function. Pulmonary hypertension, which was present in two thirds of the sample, was minimal to moderate as assessed by our Doppler technique. The effects of SCA on the heart seem to be minimal and similar to those of other anemias, predominantly confined to the left atrium and ventricle with passive elevation of pulmonary pressures. Clinical murmurs were most often physiologic; there was no association with myxomatous valvular degeneration or mitral valve prolapse.

Adult↗