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A challenging diagnosis of alpha-1-antitrypsin deficiency: identification of a patient with a novel F/Null phenotype

Michael R Ringenbach1, Erin Banta1, Melissa R Snyder3, Timothy J Craig1 and Faoud T Ishmael12*

Author Affiliations

1 Department of Medicine, Section of Allergy and Immunology, The Pennsylvania State University Milton S. Hershey Medical Center, 500 University Dr., Hershey, PA 17033, USA

2 Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, 500 University Dr., Hershey, PA 17033, USA

3 Department of Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Hilton 2-10D, 200 First St. SW, Rochester, MN, 55905, USA

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Allergy, Asthma & Clinical Immunology 2011, 7:18  doi:10.1186/1710-1492-7-18

Published: 13 November 2011


Alpha-1-antitrypsin (A1AT) deficiency is a genetic disease characterized by low levels and/or function of A1AT protein. A1AT deficiency can result in the development of COPD, liver disease, and certain skin conditions. The disease can be diagnosed by demonstrating a low level of A1AT protein and genotype screening for S and Z mutations, which are the most common. However, there are many genetic variants in A1AT deficiency, and this screening may miss rarer cases, such as those caused by dysfunctional protein. We identified a patient with a previously unreported F/null phenotype that was missed by routine screening. This case highlights the wide variation in possible mutations, limitations in diagnostics, and the importance of combining clinical suspicion with measurement of protein levels, phenotypic analysis, and in appropriate cases expanded genetic analysis.

Alpha-1-antitrypsin; diagnostic testing; phenotype; genotype