rockenmama is right - there are many folks who do not test positive for antibodies - - but who are diagnosed with MG. I'm one of them.

I received my diagnosis based on clinical exam and the symptoms I reported and my neuro could see. My one (and only) antibody test was negative, my EMG was neg. and my SFEMG was borderline. But I responded beautifully to a trial dose of Mestinon in the neuro office. So I got labelled as an MG patient and have been on Mestinon (generic) ever since!