Efgartigimod has been approved by the U.S. FDA (Food and Drug Administration) as a treatment for adult patients with gMG in whom AChR-Ab's are present. However, it was not approved it for the form of gMG that is AChR Ab seronegative (antibodies not present). and therefore this study is now testing how efragtigimod works in patients without any antibodies,

The purpose of this study is to create a biorepository of blood samples form patients with myasthenia gravis that may be used with collaborators in the development of new therapeutics for myasthenia gravis (MG).