The PiMZ Phenotype: Is it a Significant Risk Factor for the Development of Chronic Obstructive Lung Disease?1

Abstract

The PiMZ phenotype might be a significant risk factor leading to the development of chronic obstructive lung disease. That hypothesis, based on observations that the intermediate deficiency was found more often in patient groups than expected by chance alone, remains controversial. Analysis of the literature fails to resolve the controversy. The literature indicates why the studies reported to date have not yielded definitive answers. The PiMZ phenotype is sufficiently rare so that even an occasional concurrence of the severe deficiency and emphysema left no question that this state is associated with a marked increase in a person''s risk of developing chronic obstructive lung disease. Determining whether such a relationship exists for milder forms of the deficiency is a more difficult problem. The PiMZ phenotype, e.g., is found in approximately 3% of certain populations. All of the phenotypes that are associated with decreased concentrations of circulating antitrypsin can occur in as many as 10% of live births. Mild forms of the deficiency could be seen as a chance occurrence in a high proportion of patients with obstructive disease even if no excess risk existed.