Borderline HbA2 levels: Dilemma in diagnosis of beta-thalassemia carriers. Colaco, S. & Nadkarni, A. Mutation Research-reviews in Mutation Research, 788:108387, July, 2021. MAG ID: 3169981818doi abstract bibtex Abstract There is inconsistency in the exact definition of diagnostic levels of HbA2 for β thalassemia trait. While many laboratories consider HbA2 ≥4.0 % diagnostic, still others consider HbA2 ≥3.3 % or HbA2 ≥3.5 % as the cut-off for establishing β thalassemia carrier diagnosis. This is because, over the years, studies have described β thalassemia carriers showing HbA2 levels that lie above the normal range of HbA2 but below the typical carrier range of β thalassemia. These, “borderline HbA2 levels”, though not detrimental to health, are significant in β thalassemia carrier diagnosis because they can lead to misinterpretation of results. In this review, we have evaluated the prevalence of borderline HbA2 levels and discussed the causes of borderline HbA2 values. We have also compiled an extensive catalogue of β globin gene defects associated with borderline HbA2 levels and have discussed strategies to avoid misdiagnosing borderline HbA2 β thalassemia carriers. Our analysis of studies that have delineated the cause of borderline HbA2 levels in different populations shows that 35.4 % [626/1766] of all individuals with borderline HbA2 levels carry a molecular defect. Among the positive samples, 17 % [299/1766] show β globin gene defects, 7.7 % [137/1766] show α thalassemia defects, 2.7 % [49/1766] show KLF1 gene mutations, 2.3 % [41/1766] show the co-inheritance of β and α thalassemia, 2.0 % [37/1766] show the co-inheritance of β and δ thalassemia and 1.8 % [32/1766] show α globin gene triplication. It appears that a comprehensive molecular work up of the β globin gene is the only definite method to detect borderline HbA2 β thalassemia carriers, especially in populations with a high prevalence of the disease. The presence of associated genetic or acquired determinants may subsequently be assessed to identify the cause of borderline HbA2.
@article{colaco_borderline_2021,
title = {Borderline {HbA2} levels: {Dilemma} in diagnosis of beta-thalassemia carriers},
volume = {788},
doi = {10.1016/j.mrrev.2021.108387},
abstract = {Abstract There is inconsistency in the exact definition of diagnostic levels of HbA2 for β thalassemia trait. While many laboratories consider HbA2 ≥4.0 \% diagnostic, still others consider HbA2 ≥3.3 \% or HbA2 ≥3.5 \% as the cut-off for establishing β thalassemia carrier diagnosis. This is because, over the years, studies have described β thalassemia carriers showing HbA2 levels that lie above the normal range of HbA2 but below the typical carrier range of β thalassemia. These, “borderline HbA2 levels”, though not detrimental to health, are significant in β thalassemia carrier diagnosis because they can lead to misinterpretation of results. In this review, we have evaluated the prevalence of borderline HbA2 levels and discussed the causes of borderline HbA2 values. We have also compiled an extensive catalogue of β globin gene defects associated with borderline HbA2 levels and have discussed strategies to avoid misdiagnosing borderline HbA2 β thalassemia carriers. Our analysis of studies that have delineated the cause of borderline HbA2 levels in different populations shows that 35.4 \% [626/1766] of all individuals with borderline HbA2 levels carry a molecular defect. Among the positive samples, 17 \% [299/1766] show β globin gene defects, 7.7 \% [137/1766] show α thalassemia defects, 2.7 \% [49/1766] show KLF1 gene mutations, 2.3 \% [41/1766] show the co-inheritance of β and α thalassemia, 2.0 \% [37/1766] show the co-inheritance of β and δ thalassemia and 1.8 \% [32/1766] show α globin gene triplication. It appears that a comprehensive molecular work up of the β globin gene is the only definite method to detect borderline HbA2 β thalassemia carriers, especially in populations with a high prevalence of the disease. The presence of associated genetic or acquired determinants may subsequently be assessed to identify the cause of borderline HbA2.},
journal = {Mutation Research-reviews in Mutation Research},
author = {Colaco, Stacy and Nadkarni, Anita},
month = jul,
year = {2021},
doi = {10.1016/j.mrrev.2021.108387},
note = {MAG ID: 3169981818},
pages = {108387},
}
Downloads: 0
{"_id":"4vMFpif8JHkZEsdJk","bibbaseid":"colaco-nadkarni-borderlinehba2levelsdilemmaindiagnosisofbetathalassemiacarriers-2021","author_short":["Colaco, S.","Nadkarni, A."],"bibdata":{"bibtype":"article","type":"article","title":"Borderline HbA2 levels: Dilemma in diagnosis of beta-thalassemia carriers","volume":"788","doi":"10.1016/j.mrrev.2021.108387","abstract":"Abstract There is inconsistency in the exact definition of diagnostic levels of HbA2 for β thalassemia trait. While many laboratories consider HbA2 ≥4.0 % diagnostic, still others consider HbA2 ≥3.3 % or HbA2 ≥3.5 % as the cut-off for establishing β thalassemia carrier diagnosis. This is because, over the years, studies have described β thalassemia carriers showing HbA2 levels that lie above the normal range of HbA2 but below the typical carrier range of β thalassemia. These, “borderline HbA2 levels”, though not detrimental to health, are significant in β thalassemia carrier diagnosis because they can lead to misinterpretation of results. In this review, we have evaluated the prevalence of borderline HbA2 levels and discussed the causes of borderline HbA2 values. We have also compiled an extensive catalogue of β globin gene defects associated with borderline HbA2 levels and have discussed strategies to avoid misdiagnosing borderline HbA2 β thalassemia carriers. Our analysis of studies that have delineated the cause of borderline HbA2 levels in different populations shows that 35.4 % [626/1766] of all individuals with borderline HbA2 levels carry a molecular defect. Among the positive samples, 17 % [299/1766] show β globin gene defects, 7.7 % [137/1766] show α thalassemia defects, 2.7 % [49/1766] show KLF1 gene mutations, 2.3 % [41/1766] show the co-inheritance of β and α thalassemia, 2.0 % [37/1766] show the co-inheritance of β and δ thalassemia and 1.8 % [32/1766] show α globin gene triplication. It appears that a comprehensive molecular work up of the β globin gene is the only definite method to detect borderline HbA2 β thalassemia carriers, especially in populations with a high prevalence of the disease. The presence of associated genetic or acquired determinants may subsequently be assessed to identify the cause of borderline HbA2.","journal":"Mutation Research-reviews in Mutation Research","author":[{"propositions":[],"lastnames":["Colaco"],"firstnames":["Stacy"],"suffixes":[]},{"propositions":[],"lastnames":["Nadkarni"],"firstnames":["Anita"],"suffixes":[]}],"month":"July","year":"2021","note":"MAG ID: 3169981818","pages":"108387","bibtex":"@article{colaco_borderline_2021,\n\ttitle = {Borderline {HbA2} levels: {Dilemma} in diagnosis of beta-thalassemia carriers},\n\tvolume = {788},\n\tdoi = {10.1016/j.mrrev.2021.108387},\n\tabstract = {Abstract There is inconsistency in the exact definition of diagnostic levels of HbA2 for β thalassemia trait. While many laboratories consider HbA2 ≥4.0 \\% diagnostic, still others consider HbA2 ≥3.3 \\% or HbA2 ≥3.5 \\% as the cut-off for establishing β thalassemia carrier diagnosis. This is because, over the years, studies have described β thalassemia carriers showing HbA2 levels that lie above the normal range of HbA2 but below the typical carrier range of β thalassemia. These, “borderline HbA2 levels”, though not detrimental to health, are significant in β thalassemia carrier diagnosis because they can lead to misinterpretation of results. In this review, we have evaluated the prevalence of borderline HbA2 levels and discussed the causes of borderline HbA2 values. We have also compiled an extensive catalogue of β globin gene defects associated with borderline HbA2 levels and have discussed strategies to avoid misdiagnosing borderline HbA2 β thalassemia carriers. Our analysis of studies that have delineated the cause of borderline HbA2 levels in different populations shows that 35.4 \\% [626/1766] of all individuals with borderline HbA2 levels carry a molecular defect. Among the positive samples, 17 \\% [299/1766] show β globin gene defects, 7.7 \\% [137/1766] show α thalassemia defects, 2.7 \\% [49/1766] show KLF1 gene mutations, 2.3 \\% [41/1766] show the co-inheritance of β and α thalassemia, 2.0 \\% [37/1766] show the co-inheritance of β and δ thalassemia and 1.8 \\% [32/1766] show α globin gene triplication. It appears that a comprehensive molecular work up of the β globin gene is the only definite method to detect borderline HbA2 β thalassemia carriers, especially in populations with a high prevalence of the disease. The presence of associated genetic or acquired determinants may subsequently be assessed to identify the cause of borderline HbA2.},\n\tjournal = {Mutation Research-reviews in Mutation Research},\n\tauthor = {Colaco, Stacy and Nadkarni, Anita},\n\tmonth = jul,\n\tyear = {2021},\n\tdoi = {10.1016/j.mrrev.2021.108387},\n\tnote = {MAG ID: 3169981818},\n\tpages = {108387},\n}\n\n","author_short":["Colaco, S.","Nadkarni, A."],"key":"colaco_borderline_2021","id":"colaco_borderline_2021","bibbaseid":"colaco-nadkarni-borderlinehba2levelsdilemmaindiagnosisofbetathalassemiacarriers-2021","role":"author","urls":{},"metadata":{"authorlinks":{}},"html":""},"bibtype":"article","biburl":"https://bibbase.org/zotero/kountour","dataSources":["MnayAXw3qciX87bz7"],"keywords":[],"search_terms":["borderline","hba2","levels","dilemma","diagnosis","beta","thalassemia","carriers","colaco","nadkarni"],"title":"Borderline HbA2 levels: Dilemma in diagnosis of beta-thalassemia carriers","year":2021}