Inclusion Criteria:  All participants: Are able to give valid written consent are aged between the ages of 18 and 80  Stable Immunosuppressed  Have a diagnosis of AChR positive myasthenia gravis (can be ocular, bulbar or generalised) MGFA Post-intervention Status MM or better with no clinical relapse for 2 years On either azathioprine or MMF along with ≤5mg/day of prednisolone No prednisolone dose increase or decrease in past 12 months No increase in azathioprine or MMF dose for 2 years (allowing for cessation for up to 1 month)  Stable Non-Immunosuppressed  have a diagnosis of AChR positive myasthenia gravis (can be ocular, bulbar or generalised) MGFA Post-intervention Status MM or better on only low-dose cholinesterase inhibitors (≤<120 mg pyridostigmine/day) for over two years and ≤5mg/day of prednisolone for over two years. No prednisolone dose increase or decrease in past 12 months  Refractory  have a diagnosis of AChR positive myasthenia gravis (can be ocular, bulbar or generalised) have been deemed eligible to be refractory to standard treatment and eligible for rituximab as per the NHS England criteria.  Exclusion Criteria for all participants:  Are unable to give valid consent Co-existing autoimmune condition for which azathioprine or mycophenolate mofetil are treatments (e.g. inflammatory bowel disease, rheumatoid arthritis, neuromyotonia) Currently undergoing treatment for solid organ or haematological malignancy, or previous thymoma Clinical frailty scale ≥6