Treatment of Alpha-1 Antitrypsin Deficiency.

Alpha-1 antitrypsin deficiency (AATD) is a rare genetic disease that creates multiple unique phenotypes of chronic obstructive pulmonary disease. While bronchospasm, cough, dyspnea, and sputum production all occur with AATD, the phenotypic differences require a computed tomographic (CT) scan to decipher. The availability of augmentation therapy in the United States since 1989 has generated both controversy and evidence that informs the science of usual chronic obstructive pulmonary disease (COPD). Because of the predominance of emphysema in AATD, much of the best evidence concerning biomarkers of emphysema progression comes from this population. Imaging measurement of emphysema progression, impact of emphysema phenotypes on hyperinflation and dynamic hyperinflation, and correlation with traditional spirometric measures of COPD progression are required to understand the impact of AAT therapies. These studies are important for better understanding of usual COPD pathogenesis. Significantly, there are no adequately powered research studies to determine if augmentation therapy is helpful for the non-emphysema phenotypes of AATD. Specifically, phenotypes of chronic bronchitis, asthma predominant disease, and bronchiectasis will require targeted research studies to define optimal therapy.