A Study of ALN-AAT02 in Healthy Participants and Participants With ZZ Type Alpha-1 Antitrypsin Deficiency Liver Disease

Inclusion Criteria: * Male or female, aged 18 to 65 years, inclusive; * Has normal 12-lead electrocardiogram (ECG); * Has body mass index (BMI) between 18 and 30 kg/m\^2, inclusive; * Has been a nonsmoker for at least 5 years before screening; * Part A only: Has Alpha-1 antitrypsin (AAT) levels within normal limits; * Part A only: Has adequate Forced Expiratory Volume in 1 second (FEV1) and adequate FEV1/forced vital capacity ratio; * Part B only: Has documented ZZ type AAT by genotype; * Part B only: Has liver biopsy within 90 days of the first dose of study drug demonstrating ZZ type alpha-1 antitrypsin deficiency (PiZZ AATD) liver disease; * Part B only: Has adequate post-bronchodilator FEV1 and adequate diffusing capacity of the lung for carbon monoxide; * Part B only: If on any maintenance medication, is likely to be able to remain on a stable medication regimen for the duration of the study (no new medications within 30 days prior to first dose of study drug). Exclusion Criteria: * Has known human immunodeficiency virus (HIV), hepatitis C virus (HCV) or hepatitis B virus (HBV) infection; * Has clinically significant abnormal laboratory results; * Received an experimental drug within 30 days of dosing; * Has a history of multiple drug allergies or history of allergic reaction to an oligonucleotide or N-acetylgalactosamine (GalNAc); * Part A only: Has estimated glomerular filtration equal to or below 60 mL/min/1.73 m\^2 at screening; * Part A only: Has a history of asthma or recurrent or chronic lung disease, excluding resolved childhood asthma; * Part A only: Has a history of chronic liver disease; * Part B only: Has estimated glomerular filtration equal to or below 45 mL/min/1.73 m\^2 at screening; * Part B only: Received an augmentation therapy for AAT deficiency within 8 weeks of first dose of study drug; * Part B only: Has a history of chronic liver disease from any known cause other than ZZ type AAT deficiency; * Part B only: Has a history of hepatic encephalopathy; * Part B only: Has a history of gastrointestinal bleeding or ascites.