Pulmonary function associated with the Mmalton deficient variant of alpha 1-antitrypsin.

We have studied 78 members of a large family in which the Mmalton deficiency allele of alpha1antitrypsin (α1AT) is present. Four patients of PI type MmaltonZα1AT concentration, 16.4% of normal) had severe emphysema and marked depression in all flow and gas exchange parameters, significantly different from other members of the same family who were normal or had intermediate concentrations of α1AT. Fourteen subjects with PI type MMmalton (α1AT concentration, 63.3% of normal) were compared with 46 PI MM relatives (α1AT, 103.8% of normal) and 14 relatives of PI type MZ (α1AT concentration, 66.5% of normal). Spirometry, flow-volume loops, plethysmography, gas exchange at rest and exercise, and xenon 133 regional lung function were similar in those partially deficient when compared with the normal subjects. There was a trend for impairment of tests of lung function between smoking partially deficient (PI MZ, PI Mmalton) and normal (PI MM) relatives.