If a skin punch is not done at the practice,
it probably is because they have no lab for sending the samples to.
(& they may not have anyone qualified to interpret the results)

Johns Hopkins has a mail-out kit for skin punch tests,
with instructions for the doc or tech.
JHH Neuro dept is at 410-955-2227. they will probably refer you,
to call the testing lab number (sorry, I don't have it).