Thymic Disease, Autoimmunity, and Neuromuscular Junction Integrity in Myasthenia Gravis

The goal of this observational study is to investigate the clinical, immunological, and neuromuscular features associated with the development and progression of myasthenia gravis (MG) in adult patients with thymic abnormalities and/or MG-related antibodies, including individuals with or without clinically manifest disease. The main questions it aims to answer are: * Whether integrated clinical, serological, and histopathological profiles are associated with the presence of MG and can predict disease onset or progression * Wheter systemic immune markers are associated with disease activity, progression, and neuromuscular junction alterations Participants will: * Undergo clinical, neurological, and neurophysiological assessments at baseline and during follow-up * Provide blood samples for serological and immunological analyses * Provide thymic tissue and residual intercostal muscle samples (when undergoing clinically indicated thymectomy) for research analyses * Attend follow-up visits at 6, 12, and 18 months * Record daily symptoms using an electronic patient-reported outcome tool (for participants with MG)