This clinical trial is focused on studying a condition known as Hereditary Transthyretin Amyloidosis (hATTR Amyloidosis). This is a rare genetic disease where abnormal proteins build up in the body, leading to nerve damage and other health issues. The study is evaluating a treatment called ALN-TTRSC02, which is also known by its code name. This treatment is designed to help reduce the effects of the disease on the nervous system.

The purpose of the study is to assess how effective and safe ALN-TTRSC02 is for patients with hATTR Amyloidosis. Participants in the study will receive the treatment as a solution for injection. The study will also compare the effects of ALN-TTRSC02 with another treatment called Onpattro, which is given as a solution for infusion. Some participants may receive a placebo instead of the active treatment. The study will monitor changes in nerve function and quality of life over time.

Throughout the study, participants will undergo regular assessments to track their progress and any changes in their condition. The study aims to provide valuable information on how ALN-TTRSC02 can help manage the symptoms of hATTR Amyloidosis and improve the lives of those affected by this condition.