HbA2 Measurements in β-Thalassemia and in Other Conditions

Abstract

Quite a few papers have been written on the significance of elevated hemoglobin (Hb) A 2 as a parameter for the diagnosis of b-thalassemia trait, on the cutoff values to be used in diagnostics and on the significance and effects of factors reducing or elevating the expression of HbA 2 and last but not least on the need for reliable measurement methods and precise calibrations with accurate standards. However, little has been published on the causes that elevate or reduce the HbA 2 levels in b-and a-thalassemia and in other conditions. For a better understanding of the value of a precise measurement of this parameter we summarize and elucidate in this review the direct and indirect mechanisms that cause the variations in HbA 2 expression and that influence the value of this parameter in particular conditions. We conclude by explaining the advantages and disadvantages of trusting on a precise measurement in the complete diagnostic contest.

Reduced hepcidin expression enhances iron overload in patients with HbE/β‑thalassemia: Α comparative cross‑sectional study

“…Similarly, the hemoglobin level ranged from 3 to 11 g/dl depending on the phenotypes and severity of HbE/β-thalassemia patients (52). A lower hemoglobin level indicates a hypochromic state in HbE/β-thalassemia patients, where erythrocytes appear paler than normal (57). The anemic nature of HbE/β-thalassemia patients are characterized by low PCV, MCV and MCH levels (52).…”

Diagnosis and clinical relevance of co-inheritance of haemoglobin D-Punjab/β+-thalassemia traits in an immigrant Afghan family

“…The high amount of the Hb D variant with a low fraction of Hb A in absence of a history of red blood cell transfusions suggested compound heterozygosity for Hb D/β+-thalassemia. 5 The father (patient 1) was not anaemic, but a marked erythrocytosis, microcytosis and hypochromasia with normal serum ferritin levels (82 µg/L), a high amount of Hb A2 4.3% and absence of a Hb variant suggested a β-thalassemia trait (figure 1C). The other members of the family, that is, patients 3, 5, 8, 9 had a haemogram within the reference range and a normal profile at CZE, while patients 4 and 7 had a phenotype compatible with a heterozygosity for Hb D-Punjab and a beta-thalassemia trait, respectively.…”

Hemoglobin A2 and Heterogeneous Diagnostic Relevance Observed in Eight New Variants of the Delta Globin Gene

“…A δ-thal mutation would hinder the observation of Hb A 2 -X peak, but it will alter the value of Hb A 2 . This HbA 2 level will be reduced in relation to the presence of δ + or δ 0 −thal defects and, of course, will also happen in the presence of a β-thal defect [10][11][12][13]. These findings may, therefore, interfere with the accurate diagnosis of β-thal carriers.…”