If your insurance pays the tab, I would definitely get the testing!

On my ANA, it was negative for so darn long, then it went sky high...no in between. My diagnosis has been all over the map, over the 10 years it has taken. Seems like the lip biopsy 10 years ago was the best predictor of my issue....altho, it doesn't definitively identify the disease....just autoimmunity. Just because a lip biopsy is +, it doesn't mean for sure it is Sjogren's. Lately every one with Sicca, says they have SjS.

If your ANA is negative, I would definitely look at the hereditary angle....makes consumate sense to me. I am impressed your doc thought along these lines. Keep in mind, that even a negative test for hereditary neuropathy, does not rule out that issue. As Kitt said, there are many gene 'mutations'. Also, that new mutations are added every few months. It is an evolving field.

I do so hope you get answers.