This was just published in JAMA Neurology back in March. The authors conclude that there is an increased risk of a several autoimmune diseases with what they call autoimmune epilepsy.
I was diagnosed with an idiopathic ("no known cause") seizure disorder back in 2001. I took anticonvulsant drugs for three years with no additional seizures, but basically figured out my problems were gluten, diet soda, and MSG. I haven't had any seizures since then. Since then, if I get glutened ever, I typically end up with a two day migraine. So I know I have a neurologic inflammatory condition associated with gluten. I've been tested for celiac, and don't have it, but my reaction is not FODMAP related...it's to the proteins in wheat and oats.
Looking at my mom's dad's entire side of the family, it's riddled with seizures, epilepsy, and inflammatory bowel disease. I do wish I had known there was a link between this and autoimmunity, given my son's recent diagnosis of Crohn's. Of course, not much I could do other than avoid gluten and dairy and try to follow the BTD, which is basically what we've done for a long time.
I really wish my DiL would learn this!! G'daughter has epilepsy but her Mum would rather medicate than look further and even though our son would be open to this info, since she has custody of our G'daughter it is an impossible situation...
Epilepsy is a tough one. It's a lot like autism. Sometimes it's all just wiring. In my case, it was definitely diet.
Obviously, healing one's gut helps incredibly, regardless of the underlying reason. The bummer is that so many doctors have said for years that diet doesn't really do anything for any condition (except for maybe ulcers). Now, a lot of them are finally coming around! Hope someday your DIL will work with your son and you.