This is interesting...

For some reason, I was under the impression that only people with AChR antibodies would be positive for RyR antibodies, but it looks like 'seronegative' people (no Musk, no achr) can be positive for RyR antibodies as well...Maybe you seronegative guys can ask to be tested for this antibody...Since thymoma with MG is almost always positive for AchR, it would seem that those without a thymoma would also be positive for RyR...Whether these guys were older or not, it doesn't say...

It's also interesting that all the MuSk people were positive for RyR antibodies as well...

http://jnnp.bmj.com/content/76/5/714.abstract