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PLoS One. 2015 Aug 13;10(8):e0135316. doi: 10.1371/journal.pone.0135316. eCollection 2015.

How Can We Improve the Detection of Alpha1-Antitrypsin Deficiency?

Author information

1
Department of Molecular Medicine, Pneumology Unit, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
2
Department of Genetics and Clinical Immunology, National Institute of Tuberculosis and Lung Diseases, Warsaw, Poland.
3
Laboratorio Analisi, Ospedale G. Fracastoro, S. Bonifacio, ULSS20, Verona, Italy.
4
Division of Pulmonary Diseases, Department of Internal Medicine, German Center for Lung Research (DZL), Philipps-Universität Marburg, 35037, Marburg, Germany.
5
Department of Respiratory Medicine, Hannover Medical School, Biomedical Research in End stage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research (DZL), 30625, Hannover, Germany.

Abstract

The Z deficiency in α1-antitrypsin (A1ATD) is an under-recognized condition. Alpha1-antitrypsin (A1AT) is the main protein in the α1-globulin fraction of serum protein electrophoresis (SPE); however, evaluation of the α1-globulin protein fraction has received very little attention. Serum Z-type A1AT manifests in polymeric forms, but their interference with quantitative immunoassays has not been reported. Here, 214 894 samples were evaluated by SPE at the G. Fracastoro Hospital of Verona, Italy. Patients with an A1AT level ≤ 0.92 g/L were recalled to complete A1ATD diagnosis. In parallel, to qualitatively and quantitatively characterize A1AT, sera samples from 10 PiZZ and 10 PiMM subjects obtained at the National Institute of Tuberculosis and Lung Diseases in Warsaw, Poland, were subjected to non-denaturing 7.5% PAGE and 7.5% SDS-PAGE followed by Western blot. Moreover, purified A1AT was heated at 60°C and analyzed by a non-denaturing PAGE and 4-15% gradient SDS-PAGE followed by Western blot as well as by isolelectrofocusing and nephelometry. A total of 966 samples manifested percentages ≤ 2.8 or a double band in the alpha1-zone. According to the nephelometry data, 23 samples were classified as severe (A1AT ≤ 0.49 g/L) and 462 as intermediate (A1AT >0.49≤ 1.0 g/L) A1ATD. Twenty subjects agreed to complete the diagnosis and an additional 21 subjects agreed to family screening. We detected 9 cases with severe and 26 with intermediate A1ATD. Parallel experiments revealed that polymerization of M-type A1AT, when measured by nephelometry or isolelectrofocusing, yields inaccurate results, leading to the erroneous impression that it was Z type and not M-type A1AT. We illustrate the need for confirmation of Z A1AT values by "state of the art" method. Clinicians should consider a more in-depth investigation of A1ATD in patients when they exhibit serum polymers and low α1-globulin protein levels by SPE.

PMID:
26270547
PMCID:
PMC4536179
DOI:
10.1371/journal.pone.0135316
[Indexed for MEDLINE]
Free PMC Article

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