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The role of haemoglobin A2 testing in the diagnosis of thalassaemias and related haemoglobinopathies
  1. A Mosca1,
  2. R Paleari1,
  3. G Ivaldi2,
  4. R Galanello3,
  5. P C Giordano4
  1. 1Center for Metrological Traceability in Laboratory Medicine (CIRME) and Department of Science and Biomedical Technology, University of Milan, Milan, Italy
  2. 2Laboratory of Human Genetics and Microcitaemias, Ospedali Galliera, Genoa, Italy
  3. 3Laboratory of Hematology, Ospedale Regionale Microcitemie ASL8, University of Cagliari, Cagliari, Italy
  4. 4The Haemoglobinopathies Laboratory, Department of Human and Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
  1. Andrea Mosca, Dipartimento di Scienze e Tecnologie Biomediche, Via Fratelli Cervi 93, 20090 Segrate, Milan, Itlay; andrea.mosca{at}


The increase in haemoglobin (Hb)A2 level is the most significant parameter in the identification of β thalassaemia carriers. However, in some cases the level of HbA2 is not typically elevated and some difficulties may arise in making the diagnosis. For these reasons the quantification of HbA2 has to be performed with great accuracy and the results must be interpreted together with other haematological and biochemical evidence. The present document includes comments on the need for accuracy and standardisation, and on the interpretation of the HbA2 value, reviewing the most crucial aspects related to this test. A practical flow-chart is presented to summarise the significance of HbA2 estimation in different thalassaemia syndromes and related haemoglobinopathies.

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  • Funding: The work was partially supported by a grant from EC, Directorate C, Public Health and Risk Assessment, agreement N. 2004110 (ENERCA II; to AM), and by Zon-Mw project number 21000.0105 and the European Commission “Ithanet” grant number 026539 (to PCG).

  • Competing interests: None.