A Study in Adults to Learn About Inherited Alpha-1 Antitrypsin Deficiency (AATD) and AATD Related Liver Problems

Inclusion Criteria: Participants who meet all the following criteria will be included in the study. Cohorts 1 and 2: 1. Willing to provide written informed consent to participate in the study. 2. \>=18 years of age at enrollment in this study. 3. Participants with documented diagnosis of AATD, meeting the following criteria: 1. Cohort 1 (AATD-Pi\*ZZ genotype/phenotype). • Pi\*ZZ genotype as documented from rapid genetic assay, sequencing, or polymerase chain reaction (PCR), or Pi\*ZZ phenotype as documented from iso-electric focusing (IEF) electrophoresis. 2. Cohort 2 (AATD-Pi\*SZ genotype/phenotype with liver disease manifestation). * Pi\*SZ genotype as documented from rapid genetic assay, sequencing, or PCR, or Pi\*SZ phenotype as documented from IEF electrophoresis, and * Moderate-advanced or severe liver disease manifestation as defined by either liver biopsy or surrogate laboratory or imaging measures. Exclusion Criteria: Participants who meet any following criteria will be excluded from the study. 1. Documented AATD genotype/phenotype other than Pi\*ZZ or Pi\*SZ. 2. History of liver transplant. 3. No results for either biopsies, magnetic resonance elastography (MRE), FibroScan (vibration controlled transient elastography \[VCTE\]), or Aspartate aminotransferase to platelet ratio index (APRI) in the 24 months prior to the index/enrollment date and has none of these tests ordered during the index period (i.e., index date +90 days). 4. Participants with prior participation in an interventional clinical trial evaluating liver or lung disease, or who have received an investigational AATD-directed therapy under a compassionate use program, will be excluded if they do not present one of the following: * A minimum washout period of 6 months has elapsed since the last dose of the investigational product. * A history of having received placebo in prior interventional trials (to be evaluated on a case-by-case basis).