Low HbF expression in HbE-β
-thalassemia may lead to misdiagnosis of HbE heterozygosity. We aimed to characterize the β
and α-globin genes and the modifying factors related to HbF expression in ...patients with an Hb phenotype similar to that of HbE heterozygotes. Furthermore, screening tools for differentiating HbE-β
-thalassemia from HbE heterozygotes have been investigated.
A total of 2133 participants with HbE and HbA with varying HbF levels were recruited. Polymerase chain reaction-based DNA analysis and sequencing were performed to characterize β- and α-globin genes. DNA polymorphism at position -158 nt 5' to
γ-globin was performed by
I restriction digestion. Receiver operating characteristic (ROC) curves were constructed using the area under the curve (AUC). Cutoff values of HbA
, HbE, and HbF levels for the differentiation of HbE-β
-thalassemia from HbE heterozygotes were determined.
Five β
-thalassemia mutations
to β
-gene (β
, β
, β
, β
, and β
) were identified in 79 patients. Among these, 54 presented with low HbF levels, and 25 presented with high HbF levels. ROC curve analysis revealed an excellent AUC of 1.000 (95% confidence interval:1.000-1.000) for HbE levels, and a cut-off point of ≥35.0% had 100.0% sensitivity, specificity, and Youden's index for differentiating HbE-β
-thalassemia from HbE heterozygotes. The proportion of α-thalassemia mutations was 46.3 and 8.0% among HbE-β
-thalassemia patients with low and high HbF levels, respectively. Two rare α-thalassemia mutations (Cap +14(C>G) and initiation codon (ATG>-TG)) of α
-globin genes were identified. The genotype and allele of the polymorphism at -158 nt 5' to
γ-globin was found to be negatively associated with HbF expression.
HbE-β
-thalassemia cannot be disregarded until appropriate DNA analysis is performed, and the detection of α-thalassemia mutations should always be performed under these conditions. An HbE level ≥35.0% may indicate screening of samples for DNA analysis for HbE-β
-thalassemia diagnosis.
An unprespecified interim analysis of results from a phase 1–2 study of gene therapy for sickle cell disease shows resolution of severe vaso-occlusive events in 25 patients who could be evaluated. In ...the 24 months before enrollment, these patients had a median of 3.5 severe vaso-occlusive events per year.
Resumo As hemoglobinas variantes (Hb) decorrem de mutações nos genes da globina. As variantes estruturais mais frequentes são HbS, HbC, HbD e HbE. O gene da hemoglobina S tem frequência elevada na ...América, enquanto que no Brasil é maior no Sudeste e Nordeste. O presente artigo tem por objetivo investigar a presença de hemoglobinas variantes em 15 comunidades quilombolas do estado do Piauí. Foram analisadas 1.239 amostras, nas quais as hemoglobinas foram triadas pela cromatografia líquida de alta eficiência (HPLC). Aplicou-se questionário referente a gênero, etnia e consanguinidade das populações. Das 1.239 amostras, 5,4% apresentaram o traço falciforme AS, as doenças falciformes SS e SC apareceram em 0,8% do total, nas hemoglobinas AC, AD e DD. Das 1.069 pessoas negras, 84 apresentaram alteração das hemoglobinas; destas, 34 eram do sexo masculino e 53 do feminino. Ocorreu a presença de 13 casamentos consanguíneos dentre as 84 alterações das hemoglobinas. O estudo das hemoglobinas variantes em 15 comunidades remanescentes de quilombos do Piauí contribui para sua educação em saúde frente aos aspectos da herança genética destas proteínas, relevante questão de saúde pública, proporcionando subsídios para a implantação do Programa Estadual da Doença Falciforme do Piauí. Palavras-chave Doença falciforme; Traço falciforme; Saúde da população negra
A Case Study of Rare Hemoglobin Seal Rock Greenwood, Michael; Sofronescu, Alina
American journal of clinical pathology,
10/2014, Volume:
142, Issue:
suppl_1
Journal Article
Re-expression of the paralogous γ-globin genes (HBG1/2) could be a universal strategy to ameliorate the severe β-globin disorders sickle cell disease (SCD) and β-thalassemia by induction of fetal ...hemoglobin (HbF, α
γ
)
. Previously, we and others have shown that core sequences at the BCL11A erythroid enhancer are required for repression of HbF in adult-stage erythroid cells but are dispensable in non-erythroid cells
. CRISPR-Cas9-mediated gene modification has demonstrated variable efficiency, specificity, and persistence in hematopoietic stem cells (HSCs). Here, we demonstrate that Cas9:sgRNA ribonucleoprotein (RNP)-mediated cleavage within a GATA1 binding site at the +58 BCL11A erythroid enhancer results in highly penetrant disruption of this motif, reduction of BCL11A expression, and induction of fetal γ-globin. We optimize conditions for selection-free on-target editing in patient-derived HSCs as a nearly complete reaction lacking detectable genotoxicity or deleterious impact on stem cell function. HSCs preferentially undergo non-homologous compared with microhomology-mediated end joining repair. Erythroid progeny of edited engrafting SCD HSCs express therapeutic levels of HbF and resist sickling, while those from patients with β-thalassemia show restored globin chain balance. Non-homologous end joining repair-based BCL11A enhancer editing approaching complete allelic disruption in HSCs is a practicable therapeutic strategy to produce durable HbF induction.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Conspectus Sickle cell disease (SCD) is an inherited blood disorder caused by a point mutation in hemoglobin (Hb), the protein in the red blood cell (RBC) responsible for the transport of oxygen (O2) ...throughout the body. The mutation leads to the expression of sickle cell hemoglobin (HbS). Both Hb and HbS exist in equilibrium between oxygenated and deoxygenated forms; however, deoxygenated HbS can polymerize to form long fibers which distort the shape of RBCs into the characteristic sickled shape. The misshapen RBCs can obstruct blood vessels and capillaries, resulting in a vaso-occlusive crisis. Vaso-occulsion deprives tissues and organs of O2 and can cause intense pain which often results in hospitalization. Chronic organ damage is a major cause of reduced life expectancy for SCD patients. Allosteric effectors are molecules which regulate protein function. HbS allosteric effectors can be used to decrease polymerization by stabilizing the oxygenated form of HbS, which leads to an increase in O2 uptake and a decrease in the sickling of RBCs. Allosteric effectors that have been evaluated for the treatment of SCD include vanillin, 5-hydroxymethyl furfural (5-HMF), and voxelotor, which was approved by the U.S. Food and Drug Administration (FDA) for the treatment of SCD in 2019. 5-HMF did not progress to phase III clinical trials since it suffered from rapid metabolic degradation. However, several derivatives of 5-HMF and vanillin have been synthesized and evaluated as potential candidates for SCD treatment. Derivatives of these compounds have shown promise, but their shortcomings, such as high levels of oxidative metabolism, have prevented them from progressing into marketable drugs. Our efforts have produced multiple 5-HMF derivatives which have been evaluated for their potential to treat SCD. Each derivative was evaluated for its ability to increase O2 affinity (i.e., P 50, the partial pressure at which hemoglobin is 50% saturated with O2). The synthesized aryl ether derivatives were evaluated, and results suggest that compounds with multiple aromatic aldehydes may have enhanced biological properties. One such derivative, compound 5, which features two furan aldehyde rings, exhibited increased O2 affinity (P 50 = 8.82 ± 1.87 mmHg) over that of unmodified Hb (P 50 = 13.67 ± 0.22 mmHg). Future studies include obtaining crystal structures of the 5-HMF derivatives complexed with HbS to confirm the protein–allosteric effector interactions.
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IJS, KILJ, NUK, PNG, UL, UM
The likely diagnosis was homozygosity for Hb ?, a clinically benign condition common in Southeast Asia (1). Because there is no Hb A, ion exchange HPLC will not detect glycated Hb in such individuals.
Sickle cell disease (SCD) is a common, life‐threatening genetic disorder that is best managed when diagnosed early by newborn screening. However, SCD is most prevalent in low‐resource regions of the ...world where newborn screening is rare and diagnosis at the point‐of‐care is challenging. In many such regions, the majority of affected children die, undiagnosed, before the age of 5 years. A rapid and affordable point‐of‐care test for SCD is needed. The diagnostic accuracy of HemoTypeSC, a point‐of‐care immunoassay, for SCD was evaluated in individuals who had SCD, hemoglobin C disease, the related carrier (trait) states, or a normal hemoglobin phenotype. Children and adults participated in low‐, medium‐ and high‐resource environments (Ghana n = 383, Martinique n = 46, and USA n = 158). Paired blood specimens were obtained for HemoTypeSC and a reference diagnostic assay. HemoTypeSC testing was performed at the site of blood collection, and the reference test was performed in a laboratory at each site. In 587 participants, across all study sites, HemoTypeSC had an overall sensitivity of 99.5% and specificity of 99.9% across all hemoglobin phenotypes. The test had 100% sensitivity and specificity for sickle cell anemia. Sensitivity and specificity for detection of normal and trait states were >99%. HemoTypeSC is an inexpensive (<$2 per test), accurate, and rapid point‐of‐care test that can be used in resource‐limited regions with a high prevalence of SCD to provide timely diagnosis and support newborn screening programs.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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