AChR Myasthenia Gravis

The goal of the AXIS Autoimmune Neurology Registry is to learn about the experiences of adults living with autoimmune neurological disorders, starting with myasthenia gravis (MG), over time. The main questions the registry aims to answer are: * How do symptoms, daily functioning, and quality of life change over time? * What treatments do participants use, and how are these treatments related to their symptoms and health? * What challenges do participants experience with treatment, including side effects, treatment burden, missed doses, and access to care? Participants will: * Join the registry and complete an enrollment survey (online or through a mobile app) * Complete a brief online survey about their MG approximately once a month * Provide information that can help confirm their MG diagnosis * Optionally, share their medical records with the research team This is an observational study. The registry will not assign treatments or ask participants to change their medical care. Information collected through the registry may help researchers better understand MG and improve future research and care.

This study plans to learn more about if the drug efgartigimod can be used in the hospital to treat exacerbations in participants with myasthenia gravis (MG). Efgartigimod has been approved by the FDA for ongoing (chronic) treatment of generalized MG in adult patients who are anti-acetylcholine receptor (AChR) antibody positive but has not been studied in the treatment of worsening weakness requiring hospital admission (known as "exacerbation"). This investigation aims to see if using efgartigimod in this way improves symptoms and recovery from exacerbation, and how it affects certain MG markers in the blood. The main questions it aims to answer are: * Is efgartigimod effective as a hospital-administered acute therapy for participants with worsening MG (MG exacerbation) who require hospitalization? * Will efgartigimod lead to clinical improvement with a similar reduction in validated research scales, such as the Quantitative MG (QMG) scale, as standard of care therapies? Participants will receive 4 doses of efgartigimod over the course of 4 weeks with an additional follow-up visit at the clinic.