Hi, Serena. I hope some of the knowledgeable people around here will chime in, but a few things stand out to me.

First, there are other antibodies besides the AChR antibodies that they can test for, such as the MuSK and LEMS antibodies. They should test you for these. Second, it's pretty common to test negative for the AChR antibodies at one point--especially early in the disease--and test positive later. And third, there are many people here (myself included) who are diagnosed with MG even though we never got a positive blood test for any of the antibodies.

A person in your position should certainly have a Single Fiber EMG! I am really surprised that you haven't had this test. It's a pretty specialized skill--not every neurologist (or even every neurologist who studies in neuromuscular diseases) can do it, but they should send you to someone who can.

Did your father ever test positive for the antibodies? I ask because with these symptoms in the family, someone should be looking into congenital mysasthenic syndromes. CMS is not an autoimmune disease, but a genetic one.

My MG symptoms are pretty atypical. I have never had ptosis, or not enough to really notice--one neurologist thinks I have it, but I'm not sure. My eyes are hardly affected at all. My first symptoms looked like ataxia--I was walking funny and having trouble keeping my balance. It took me months to understand that the trouble was caused by weak muscles in my hips and sides. The first doctor I went to thought it was an inner-ear virus, because it looked like a balance problem.

I hope you get some answers really soon. I know how hard it is to be in limbo like this.

Abby