A necropsy study of Pi phenotypes, emphysema, and smoking.

Pi phenotypes, determined post mortem by isoelectric focusing and immunofixation, emphysema, assessed from inflation fixed specimens and smoking history were correlated in 186 hospital necropsies. It was possible to determine Pi phenotype in 98.4% of the specimens. Phenotype M occurred in 87.5%, MZ in a 8.1%, MS in 2.1% and FM in 0.5%. An expected association was found between smoking and emphysema but not between the Pi phenotypes and emphysema. Thus, while smoking is a major aetiological factor, the Pi MZ heterozygous state does not seem to predispose to structural emphysema. However, the small number of cases did not allow an estimation of the risk of smoking in Pi MZ heterozygous persons compared to those with the normal Pi phenotype.