Rationale and Design of the Alpha-1 Biomarkers Consortium Study.

Rationale: Alpha-1 antitrypsin deficiency (AATD) is the most common genetic cause of chronic obstructive pulmonary disease (COPD), but considerable phenotypic variability exists among affected individuals who share disease-causing variants. Therefore, a multicenter longitudinal cohort study of 270 adult participants with PiZZ AATD will be established with a goal of examining how computed tomography (CT) imaging and serum and airway biomarkers can be used to explain differences in phenotypic manifestations and outcomes.

Methods: Study visits at enrollment, 18 months, and 36 months will obtain spirometry, patient-reported outcomes, and biosampling from blood, nasal mucosa, and sputum. Chest CT image acquisition will be utilized for whole lung and lobar estimations of emphysema based on lung density and to test novel measurements of airway remodeling and lung tissue mechanics. Dried blood spot cards will be collected if the participant experiences an acute exacerbation of COPD during the study. Genetic analysis will be performed with complete sequencing, and peripheral blood mononuclear cells will be isolated to generate a repository of inducible pluripotent stem cells.

Results: The cohort will be deeply characterized, including imaging, physiology, and symptomatology, cross-sectionally and longitudinally over a 3-year follow-up period. A validation cohort from Ireland will independently enroll patients with identical procedures.

Conclusion: This is the first cohort of AATD to incorporate such detailed metrics of disease, including quantitative emphysema measures, with the overarching goal of improving the understanding of disease heterogeneity in AATD and identifying factors associated with disease severity and progression.