--along with some testing from Specialty Labs of Van Nuys, CA--and not only do they do a lot of herediatry/genetic testing, they also can do testing for some of the more obscure causes of small-fiber neuropathy. My amyloid testing, for instance, was done through them (and, given your autonomic symptoms, this is definitely one possibility I though of). I also had specialized Epstein Barr titres done through them to measure antibody levels to specific antigens, the pattern of which can often point to certain obscure cancers (fortunately, didn't have any of those).

Do let us know exactly what tests are ordered--get a complete list, even if only abbreviations--we can figure 'em out.