What is his age, sorry if I missed that..

I'm not a MG expert but I think many take mestion, was that tried?
Our MG forum has a lot of info. Yes you can copy your post there..

Possible secondary issue..
Might look into past environmental or exposure factors, EMFs, chemical exposures, overseas travels, military service/deployments.
Even where he grew up, possibly a risky or polluted area..
If you find a connection, maybe that will point to a condition caused by those....
Relatives with anything similar or other rare conditions?

Genetic testing? like 23and me - Compare our DNA Tests - 23andMe