AAT Phenotype Identification by Isoelectric Focusing

  • Dina N. Greene
  • M. C. Elliott-Jelf
  • David G. Grenache
Part of the Methods in Molecular Biology book series (MIMB, volume 1639)


Isoelectric focusing (IEF) electrophoresis is considered to be the gold standard test for determining an individual’s AAT phenotype. IEF electrophoresis is a technique used to separate proteins by differences in their isoelectric point (pI). Testing is performed on serum that is applied to an agarose gel containing ampholytes which create a pH gradient ranging from 4.2 to 4.9. Variants of AAT are therefore separated from each other and, after visualization of the focused protein bands using immunochemical techniques, can be identified and an AAT phenotype determined.

In this chapter we elaborate on IEF electrophoresis as it relates to AAT phenotyping, describe practical approaches to AAT variant identification, and discuss circumstances in which phenotype testing may be inaccurate.

Key words

Isoelectric focusing electrophoresis Immunofixation Immunodetection Alpha-1 antitrypsin phenotyping Test interpretation 


  1. 1.
    Burtis C, Ashwood E, Bruns D (eds) (2011) Tietz textbook of clinical chemistry and molecular diagnostics, 5th edn. Elsevier, AmsterdamGoogle Scholar
  2. 2.
    Zerimech F, Hennache G, Bellon F et al (2008) Evaluation of a new Sebia isoelectrofocusing kit for alpha 1-antitrypsin phenotyping with the Hydrasys system. Clin Chem Lab Med 46:260–263CrossRefPubMedGoogle Scholar
  3. 3.
    Greene D, Elliott-Jelf M, Straseski J et al (2013) Facilitating the laboratory diagnosis of α1-antitrypsin deficiency. Am J Clin Pathol 139:184–191CrossRefPubMedGoogle Scholar
  4. 4.
    Greene D, Procter M, Krautscheid P et al (2012) α1-antitrypsin deficiency in fraternal twins born with familial spontaneous pneumothorax. Chest 141:239–241CrossRefPubMedGoogle Scholar
  5. 5.
    BB S-L, Procter M, Krautscheid P et al (2014) Challenging identification of a novel PiISF and the rare PiMmaltonZ α1-antitrypsin deficiency variants in two patients. Am J Clin Pathol 141:742–746CrossRefGoogle Scholar
  6. 6.
    Bornhorst J, Greene D, Ashwood E et al (2013) α1-antitrypsin phenotypes and associated serum protein concentrations in a large clinical population. Chest 143:1000–1008CrossRefPubMedGoogle Scholar
  7. 7.
    Donato L, Jenkins S, Smith C et al (2012) Reference and interpretive ranges for α(1)-antitrypsin quantitation by phenotype in adult and pediatric populations. Am J Clin Pathol 138:398–405CrossRefPubMedGoogle Scholar

Copyright information

© Springer Science+Business Media LLC 2017

Authors and Affiliations

  • Dina N. Greene
    • 1
  • M. C. Elliott-Jelf
    • 2
  • David G. Grenache
    • 2
    • 3
  1. 1.Department of Laboratory Medicine, Chemistry DivisionUniversity of WashingtonSeattleUSA
  2. 2.ARUP Institute for Clinical and Experimental PathologySalt Lake CityUSA
  3. 3.Department of PathologyUniversity of Utah School of MedicineSalt Lake CityUSA

Personalised recommendations