A Study About Fazirsiran in People With and Without Liver Problems

Inclusion Criteria: Key Inclusion Criteria for All Participants * A 12-lead ECG at screening that, in the opinion of the investigator, has no abnormalities that compromise the participant's safety in this study. * No abnormal finding of clinical relevance at screening or before dosing that in the opinion of the investigator could adversely impact participant safety during the study or adversely impact study results. Key Inclusion Criteria for Participants with Hepatic Impairment: * The participant is 18 to 75 years of age inclusive at the time of signing the informed consent form (ICF). * The participant has a body mass index (BMI) greater than or equal to (\>=) 18.0 and less than or equal to (\<=) 40.0 kilograms per square meter (kg/m\^2) at screening. * Aside from HI, the participant must be sufficiently healthy for study participation based upon medical history, physical examination, vital signs, electrocardiograms (ECGs), and screening clinical laboratory profiles, as deemed by the investigator or designee. * Diagnosis of chronic (example, imaging, biopsy, etc.) stable hepatic insufficiency for at least 3 months before screening with features of cirrhosis due to any etiology according to medical history. HI must be stable, that is, no significant changes in hepatic function or clinical status in the 30 days preceding screening (or since the last visit if within 3 months before screening) and with treatment with stable doses of medication. * Has a Child-Turcotte-Pugh (…