The main purpose of this study is to evaluate how much lepodisiran gets into the blood stream and how long it takes the body to get rid of it when given as a subcutaneous (SC) injection under the skin to participants with mild, moderate, or severe liver function impairment compared to participants with normal liver function. The study will also evaluate how well lepodisiran is tolerated and what side effects may occur in these participants.

The study will last up to approximately 9 weeks, excluding screening.

Inclusion Criteria:

• Have a body weight of 55 kilogram (kg) or more and body mass index within the range 19.0 to 42.0 kilogram per square meter (kg/m²)

• Additional Inclusion Criteria for Participants Without Hepatic Impairment in Group 1:

  • Healthy participants with clinically normal hepatic function

• For Participants with Mild to Severe Hepatic Impairment in Groups 2 through 4:

  • Participants with hepatic impairment classified as Child-Pugh score A, B, or C (mild, moderate, or severe impairment). Diagnosis of chronic hepatic impairment of greater than 6 months, per physician diagnosis and standard-of-care practice

Exclusion Criteria:

• Have significant history of, or current, cardiovascular (CV), respiratory, hepatic (hepatic applies to Group 1 only), renal, gastrointestinal, endocrine, hematological, or neurological disorders
• Have severe atopy or a history of clinically significant multiple or severe drug allergies
• Have known allergies to lepodisiran, related compounds, or any components of the formulation
• Have a history of, or current, psychiatric disorders
• Have had any malignancy within the past 5 years
• Have estimated glomerular filtration rate (eGFR) less than 60 milliliters per minute per 1.73 m² (mL/min/1.73 m²) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation
• Have participated, within the last 1 month, in a clinical study involving an investigational product