This study tests a drug called **Tofersen** for adults who have a genetic change called **Superoxide Dismutase 1 (SOD1) mutation**. A mutation is a change in a gene. People with this mutation can develop a disease called **amyotrophic lateral sclerosis (ALS)**, which affects muscles. The study will check if Tofersen helps before any symptoms appear. **Neurofilament (NF)** is a protein that can be high in people with nerve damage, and this study checks its levels too.

To join, participants should have a specific SOD1 mutation and a low NF level. They should not have symptoms of ALS.

• **Length**: The study involves multiple visits but exact length isn't mentioned.
• **Risks**: Participants must not have certain infections or be on certain medications.
• **Compensation**: Not mentioned.

Before joining, participants should ensure they fit the criteria and understand the visit schedule and any risks involved. The study will look at Tofersen's safety, how well people tolerate it, and its effects.