What this Trial Is About

In this study, researchers will learn more about the safety of tofersen, also known as Qalsody®. This is a drug available for doctors to prescribe for participant with a certain type of amyotrophic lateral sclerosis, also known as ALS. This type is in participant who have a mutation in the superoxide dismutase 1 gene, also known as SOD-1. This is known as an "observational" study, which collects health information about study participants without changing their medical care. Participants for this study will be found using 2 different groups of study research centers that help provide clinical care for participant with ALS. These groups are in Europe and the United States and are called: * the Precision-ALS programme * the ALS/Motor Neuron Disease (MND) Natural History Consortium (NHC) The main goal of this study is to collect safety information in participants with SOD-1 ALS who were in either of the groups. The main question researchers want to answer in this study is: * What are the characteristics of the participants in this study? * How many participants had serious adverse events (SAEs), including ones that affect the brain, spinal cord, or nerves? An adverse event is a health problem that may or may not be caused by a drug during the study. An adverse event is considered serious when it results in death, is life-threatening, causes lasting problems, or requires hospital care. Researchers will also learn more about: * How many participants develop other health conditions or become pregnant, including how the pregnancy turned out * Why and when participants stopped treatment This study will be done as follows: * Participants will be screened to check if they can join the study. * Data from the participants' regular visits to their clinic will be collected based on which study research center they are in. * Each participant will be in the study until they decide to leave or until death. Currently, the study is planned to last at least 7 years.

A Study to Learn More About the Long-Term Safety of Tofersen (Qalsody) in Participants With Superoxide Dismutase 1 (SOD-1) Amyotrophic Lateral Sclerosis (ALS)