There is Ehlers Danlos Syndrome that runs in families and can go undetected or misdiagnosed. This can cause neurological and connective tissue problems and very commonly dysautonomia. I'm pretty sure I have it...or at least I have every single symptom, but autoimmune diseases can look similar. I'm betting they will check me for this when I go to Columbia.

Also there are metabolic disorders that run in families. I'm finding that people go years with out a proper diagnosis until they finally get a geneticist. My one neurologist didn't see the point since I already have a "diagnosis", but I think it's important to find a cause so you know what to treat and not to treat and to stop guessing.