Developing New Ways to Detect Respiratory Impairment Early in ALS

The goal of this observational study is to develop new ways to detect early changes associated with amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease. The study will examine whether changes in breathing, magnetic resonance imaging (MRI) of the brainstem and spinal cord, and blood markers can identify early signs of ALS before major physical changes occur. The main questions the study aims to answer are: * Can changes in automatic breathing help identify early ALS-related changes? * Can breathing measures distinguish people with ALS from people without ALS? * Do people with genetic risk for ALS who show changes in breathing also have changes in the brainstem and spinal cord or higher levels of blood markers associated with nerve damage? Participants will complete breathing and muscle function tests, an MRI scan of the brainstem and spinal cord, and blood testing. The study will include people with ALS, people with genetic risk for ALS who do not yet have symptoms, and healthy adults for comparison.