It would be really nice if they did the skin biopsy at this stage (early). This way you have a good base line at the start of problems and the test can be repeated as necessary to document progression.

Of course, what would be beneficial to you and what they actually do for next testing may be entirely different things. In my opinion, it makes no sense to wait until the patient is miserable with symptoms before documenting it with skin biopsy...then they may be too far along to reap the benefits of some treatments. Push for them to continue the search NOW while this is still in early stages! You have an opportunity to get a jump on a Dx that most of us never had.