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Horri-Naceur A, Timson DJ. In Silico Analysis of the Effects of Point Mutations on α-Globin: Implications for α-Thalassemia. Hemoglobin 2020; 44:89-103. [PMID: 32420790 DOI: 10.1080/03630269.2020.1739067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Hemoglobinopathies are inherited diseases that impair the structure and function of the oxygen-carrying pigment hemoglobin (Hb). Adult Hb consists of two α and two β subunits. α-Thalassemia (α-thal) affects the genes that code for the α-globin chains, HBA1 and HBA2. Mutations can result in asymptomatic, mild or severe outcomes depending on several factors, such as mutation type, number of mutations and the location at which they occur. PredictSNP was used to estimate whether every possible single nucleotide polymorphism (SNP) would have a neutral or deleterious effect on the protein. These results were then used to create a plot of predicted tolerance to change for each residue in the protein. Tolerance to change was negatively correlated with the residue's sequence conservation score. The PredictSNP data were compared to clinical reports of 110 selected variants in the literature. There were 29 disagreements between the two data types. Some of these could be resolved by considering the role of the affected residue in binding other molecules. The three-dimensional structures of some of these variant proteins were modeled. These models helped explain variants which affect heme binding. We predict that where a point mutation alters a residue that is intolerant to change, is well conserved and or involved in interactions, it is likely to be associated with disease. Overall, the data from this study could be used alongside biochemical and clinical data to assess novel α-globin variants.
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Affiliation(s)
- Agathe Horri-Naceur
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, East Sussex, UK
| | - David J Timson
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, East Sussex, UK
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Kimura EM, Oliveira DM, Jorge SE, Ribeiro DM, Zaccariotto TR, Santos MNN, Almeida V, Albuquerque DM, Costa FF, Sonati MDF. Investigating alpha-globin structural variants: a retrospective review of 135,000 Brazilian individuals. Rev Bras Hematol Hemoter 2015; 37:103-8. [PMID: 25818820 PMCID: PMC4382568 DOI: 10.1016/j.bjhh.2015.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 09/30/2014] [Indexed: 12/04/2022] Open
Abstract
Background Brazil has a multiethnic population with a high diversity of hemoglobinopathies. While screenings for beta-globin mutations are far more common, alterations affecting alpha-globin genes are usually more silent and less well known. The aim of this study was to describe the results of a screening program for alpha-globin gene mutations in a representative sample of the Southeastern Brazilian population. Methods A total of 135,000 individuals, including patients with clinical suspicion of hemoglobinopathies and their family members, randomly chosen individuals submitted to blood tests and blood donors who were abnormal hemoglobin carriers were analyzed. The variants were screened by alkaline and acid electrophoreses, isoelectric focusing and cation-exchange high performance liquid chromatography (HPLC) and the abnormal chains were investigated by reverse-phase high performance liquid chromatography (RP-HPLC). Mutations were identified by molecular analyses, and the oxygen affinity, heme–heme cooperativity and Bohr effect of the variants were evaluated by functional tests. Results Four new and 22 rare variants were detected in 98 families. Some of these variants were found in co-inheritance with other hemoglobinopathies. Of the rare hemoglobins, Hasharon, Stanleyville II and J-Rovigo were the most common, the first two being S-like and associated with alpha-thalassemia. Conclusion The variability of alpha-globin alterations reflects the high degree of racial miscegenation and an intense internal migratory flow between different Brazilian regions. This diversity highlights the importance of programs for diagnosing hemoglobinopathies and preventing combinations that may lead to important clinical manifestations in multiethnic populations.
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Affiliation(s)
- Elza Miyuki Kimura
- Department of Clinical Pathology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil; National Institute of Blood Science and Technology, National Council for Scientific and Technological Development (CNPq), Ministry of Science and Technology (MCT), Brazil
| | - Denise Madureira Oliveira
- Department of Clinical Pathology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil; National Institute of Blood Science and Technology, National Council for Scientific and Technological Development (CNPq), Ministry of Science and Technology (MCT), Brazil
| | - Susan Elisabeth Jorge
- Department of Clinical Pathology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil; National Institute of Blood Science and Technology, National Council for Scientific and Technological Development (CNPq), Ministry of Science and Technology (MCT), Brazil
| | - Daniela Maria Ribeiro
- Department of Clinical Pathology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil; National Institute of Blood Science and Technology, National Council for Scientific and Technological Development (CNPq), Ministry of Science and Technology (MCT), Brazil
| | - Tânia Regina Zaccariotto
- Department of Clinical Pathology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil; National Institute of Blood Science and Technology, National Council for Scientific and Technological Development (CNPq), Ministry of Science and Technology (MCT), Brazil
| | - Magnun Nueldo Nunes Santos
- Department of Clinical Pathology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil; National Institute of Blood Science and Technology, National Council for Scientific and Technological Development (CNPq), Ministry of Science and Technology (MCT), Brazil
| | - Vanessa Almeida
- Department of Clinical Pathology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil; National Institute of Blood Science and Technology, National Council for Scientific and Technological Development (CNPq), Ministry of Science and Technology (MCT), Brazil
| | - Dulcinéia Martins Albuquerque
- National Institute of Blood Science and Technology, National Council for Scientific and Technological Development (CNPq), Ministry of Science and Technology (MCT), Brazil; Hematology and Hemotherapy Center, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Fernando Ferreira Costa
- National Institute of Blood Science and Technology, National Council for Scientific and Technological Development (CNPq), Ministry of Science and Technology (MCT), Brazil; Hematology and Hemotherapy Center, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Maria de Fátima Sonati
- Department of Clinical Pathology, School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil; National Institute of Blood Science and Technology, National Council for Scientific and Technological Development (CNPq), Ministry of Science and Technology (MCT), Brazil.
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