Long-term, multicenter, multinational, observational, registry of patients with gMG that is designed to collect data on clinical outcomes and safety in patients prescribed Alexion C5 inhibitor therapies (C5IT) such as eculizumab (Soliris®) and ravulizumab (Ultomiris®).

At the time of enrollment in the Registry, participant records will be queried for retrospective information about the participants' medical history and gMG disease treatment history. Following enrollment, prospective data collection will be performed using data obtained as part of the routine clinical care and through patient-reported outcome methods in use. Data will be collected using an electronic data capture system. The duration of data collection for the Registry will be up to 5 years from the day of enrollment.

Inclusion Criteria:

1. Participants with a diagnosis of gMG who are treated with Alexion C5IT at the time of enrollment, including patients previously treated with Soliris or Ultomiris and withdrawn from treatment.
2. Capable of giving signed informed consent, which includes compliance with the protocol requirements and restrictions.
3. Participants must have myasthenia gravis historical data, such as MG-ADL and MGFA class, available to be enrolled in the Registry.

Exclusion Criteria:

1. Participants currently enrolled in an Alexion-sponsored interventional clinical study for treatment of gMG cannot be enrolled in the Alexion gMG Registry while enrolled/participating in the clinical study for gMG therapy.

Participants with a diagnosis of gMG who are treated with Alexion C5IT at the time of enrollment, or have ever been treated with Alexion C5IT prior to enrollment, and meet the inclusion criteria and exclusion criteria are eligible for registry participation.