I have a close friend who I originally met here on PR in 2014 (who has not posted here in about 4 yrs) who tested positive for Ganglionic AChR Antibodies and was given a diagnosis of Autoimmune Autonomic Ganglionopathy (AAG) among several other diagnoses. I can ask her more about this if it would be helpful for either of you. She and I both got tested w/the same Mayo Panels by Stanford in 2016 but each got different results (I tested positive for N-type CA+ Channel Autoantibody and Anti-GAD65 and she tested positive for Ganglionic AChR Antibodies).
I know this was addressed to @crypt0cu1t
but I was surprised to see anti-GAD65 linked to AE and I hadn't seen that before! Anti-GAD65 seems to link to so many different things. I tested positive for GAD65 at a high level on Mayo Panels in 2016 and then a few years later my level was significantly lower (but still positive) after IVIG & Rituximab. We measured it again out of curiosity to see if it was lower but it was never the focus of my treatment and it was the autoantibody that I was never certain what it linked to (in my case).
Anti-GAD65 most commonly links to diabetes and SPS (Stiff Person Syndrome) but I never had either of those. I later found info that Anti-GAD65 also links with Dysautonomia & Hashimoto's (and I had both of those) and we assumed that was the link for me. I also had an extremely exaggerated startle reflex (which links to higher glutamate and lower GABA which is the exact mechanism of Anti-GAD65 in that it attacks the enzyme that converts glutamate to GABA). The IVIG completely eliminated my exaggerated startle reflex although this again was an extra bonus and not the focus of my treatment.
On a side note, my doctor decided that it was not worth it for me to continue to test for additional autoantibodies after we found that I had 11 different ones (in 2016). He said that it was interesting on an academic level because I had the most severe/clear-cut autoimmunity of all of his patients, but that it wouldn't change my treatment plan (which was high dose IVIG & then Rituximab) no matter how many additional autoantibodies we found.
I always wondered if I had (or still have?) additional autoantibodies but was not sure if having that info would make any difference, especially since my treatment led to remission of all of my core symptoms. And (so far), I have maintained the remission for over one year after stopping Rituximab. One thing we were curious about (in light of other problems not related to my core symptoms) is if I have autoantibodies against the pituitary which affect my ability to create ACTH. But there is not a commercial test for this plus it is too challenging to pursue during COVID.
I am similar to @crypt0cu1t
(although we each have different diagnoses & symptoms) in the sense that I had the symptoms of LEMS (but never tested positive for the most common LEMS autoantibody which is the P/Q Calcium Channel Ab and instead tested positive repeatedly for the N-type). And @crypt0cu1t
(if I understand correctly), you are negative for anti-NMDR but positive for other Auto-Abs that link to AE? I think there are just people who are atypical cases of everything even if many neurologists cannot understand this.
Edited to Add: One area where testing for the specific auto-antibodies is crucial is with the paraneoplastic autoantibodies that link with cancer b/c then you can have the corresponding tests to rule out cancer as the cause (versus autoimmunity as the cause).