Assessment of alpha-1-antitrypsin deficiency heterozygosity as a risk factor in the etiology of emphysema. Physiological comparison of adult normal and heterozygous protease inhibitor phenotype subjects from a random population.

For plethysmographic studies of lung mechanics and measurement of pulmonary diffusing capacity, 62 subjects were drawn from a randomly selected population sample. Data obtained from the 24 subjects of heterozygous phenotype for alpha-1-antitrypsin deficiency (PiMZ) were compared by age group with data from 38 normal (PiM) subjects matched for sex, age, and smoking history. Comparison of mean values by age group for lung volumes, diffusing capacity, lung elastic recoil, maximum expiratory flow, and the occurrence of frequency dependence of dynamic compliance revealed no differences between phenotype groups. There was no evidence of an accelerated effect of aging among PiMZ subjects when compared with normal counterparts nor was there evidence of an increased effect of smoking. From these data it appears that the PiMZ phenotype per se is not a risk factor in the development of emphysema.