Tissue Repository for Studies of Myasthenia Gravis

This is a bio-specimen collection study. The investigators will collect plasma and peripheral lymphocytes. Plasma will be collected either when the patient undergoes plasma exchange, a decision independent of this study, or through a scheduled blood draw. Patient plasma will be screened for novel antibodies which may cause myasthenia gravis. Subjects that are found to be positive for candidate antigens for myasthenia gravis will have a clinical evaluation which will consist of several disease rating scales will be performed (QMG score, MG-composite, Myasthenia Gravis Foundation of America (MGFA) clinical classification, MG-Quality of Life (QOL)15, MGFA Therapy Status).