Alpha 1-antitrypsin deficiency and the flaccid lung syndrome. The heterozygote controversy.

A significantly higher number of PI ZZ and PI MZ individuals was found in a flaccid lung population as compared to internal and healthy controls. The relative risk for ZZ is 12.5 and for MZ 1.8. We conclude that if a PI MZ individual does develop lung disease, the excess risk due to the deficiency is negligible compared to MM individuals and is highly influenced or modified by other factors, possibly including both environmental and genetic.