Open Label Study of Subcutaneous Immunoglobulin (SCIg) in Myasthenia Gravis

Inclusion Criteria:

* Patients 18 and older
* Patients must have prior or current documentation of MGFA MG grades 2, 3, or 4 generalized MG, according to the MGFA classification system.48 These grades correspond to mild (2), moderate (3), and severe (4)
* Elevated AChR or MuSK Ab. These tests will have been performed at some time prior to entry into the study. Double seronegative MG patients with prior documentation of an abnormal decrement (\>10%) on slow repetitive nerve stimulation or an abnormal single fiber EMG will also be allowed to participate
* Patient's signs and symptoms should not be better explained by another disease process.
* IVIg maintenance dose of 0.2 to 2 gm/kg/4 weeks or equivalent dose administered Q 2-4 weeks±3days
* Stable IVIg for at least 3 cycles (definition of stability: no change in prescribed dosage or frequency by the treating physician)
* Patient must be receiving no more than 200g/4weeks of IVIg.
* Patients must be willing to complete the study and return for follow-up visits.
* Patients must be willing to give written informed consent before participating in this study. A copy of the signed consent must be kept in the patient's medical record.
* Patients can be on the following drugs as long as there has been no dose change for 60 days: azathioprine, cyclosporine, cyclophosphamide, mycophenolate mofetil, tacrolimus, methotrexate or other immunosuppressive drugs.
* Patients can be on prednisone as long as there has been no dose change for 30 days.

Exclusion Criteria:

* MGFA grade V within 6 months of screening.
* A history of chronic degenerative, psychiatric, or neurologic disorder other than MG that can produce weakness or fatigue.
* Other major chronic or debilitating illnesses within six months prior to study entry.
* Female patients who are premenopausal and are: (a) pregnant on the basis of a serum pregnancy test, (b) breast-feeding, or (c) not using an effective method of double barrier (1 hormonal plus 1 barrier method or 2 simultaneous barrier methods) birth control (birth control pills, male condom, female condom, intrauterine device, Norplant, tubal ligation, or other sterilization procedures).
* Altered levels of consciousness, dementia, or abnormal mental status.
* Thymectomy in the previous three months.
* Evidence of renal insufficiency (Cr\>1.5 x elevated) or liver disease (transaminases \> 2.5 x elevation) at screening.
* Skin disease that would interfere with assessment of injection site reaction
* History of severe reactions to IVIg or SCIg.
* Participation in a research study within the last 3 months
* Treatment with rituximab or other biologics within 12 months of study entry
* Inability to provide informed consent.
* History of thrombotic episodes within the last year prior to enrollment
* Known allergic or other severe reactions to blood products including intolerability to previous normal human immunoglobulin for intravenous administration (IVIG) and/or subcutaneous immunoglobulin (SCIG), such as history of clinically relevant hemolysis after IVIG infusion, aseptic meningitis, recurrent severe headache, hypersensitivity, severe generalized or severe local skin reaction.
* History of IgA deficiency or evidence of IgA deficiency at screening.