Myasthenia gravis (MG) is an autoimmune disease caused by dysfunction at the neuromuscular junction, characterized by partial or generalized skeletal muscle weakness and fatigability. The estimated annual incidence rate of MG in China is 0.68/100,000, with a high rate of relapse and poor treatment compliance. This study is a prospective, observational, multi-center patient registry across China. To support standardized management and follow-up of MG patients in China, a Cloud-based MG Patient Management Platform (CN MG Base) was established in September 2023 with the support of the Chinese Rare Diseases Alliance. The platform aims to collect longitudinal clinical data including demographic information, age of onset, medical history, comorbidities, medication usage, treatment responses, and others. It is intended to collect newly registered MG cases each year and follow up with these patients at one-year intervals for ten years

This study is a observational nationwide multicenter MG registry research. Starting from the baseline, annual follow-ups will be conducted to prospectively collect information on treatment medications, prognosis, and safety events. The following classification definitions can be applied: ① MG clinical subtypes (ocular, early-onset generalized, thymoma-related, late-onset generalized, MuSK-related, and seronegative); ② Different treatment methods (classic immunotherapy group, B-cell-targeted therapy, complement inhibition therapy, rapid-acting therapy, and IL-6 pathway inhibitors, etc.).

Inclusion Criteria:

• Fluctuating weakness in skeletal muscles, such as extraocular, bulbar, limb muscles, etc.. Demonstrating fluctuation and fatigability: Weakness is usually worse in the morning and improves with rest; worsens with sustained activity.
• Patients themselves or their guardians can understand and sign the informed consent form.

To meet the eligibility criteria, at least one of the following additional criteria must be met:

• a. Positive Tensilon test;
• b. Decrease in compound muscle action potential by more than 10% with low-frequency repetitive nerve stimulation or widening of the "jitter" (the variability in time of the second action potential relative to the first) on single-fiber electromyography, with or without blocking;
• c. Positive antibodies: Serum testing positive for AChR antibodies, MuSK antibodies, or LRP4 antibodies.

Exclusion Criteria:

• Patients with mental illness who cannot cooperate.
• Patients with multiple organ dysfunction or in extremely critical condition, unable to complete relevant medical history collection or evaluation.

MG patients mostly of Chinese Han ethnicity (ocular MG type no more than 30%).