RecruitingPhase 3Biological interventionSeronegative Myasthenia Gravis - Efgartigimod IVThis is to study the efficacy, safety and tolerability of efgartigimod in patients with seronegative generalized myasthenia gravis. This is an open label study. There will be 30 participants to enroll at University Health Network Toronto General Hospital. Study duration is 43 weeks from screening to end of study.