Hello @meredithmunro, Welcome to Mayo Clinic Connect. I have idiopathic small fiber peripheral neuropathy that I suspect may be hereditary but have not looked into the testing specifics for neuropathy. I do have a cousin with similar autoimmune diseases polymalagia rheumatica and small fiber PN which I also have. For me, if I found out it was hereditary it wouldn't make any difference in a treatment since there is no medical treatment that will fix numbness (my only symptom). There are a few other discussions that you may want to read through or join to learn what other members have shared.

Unknown Cause or Idiopathic SFN: https://connect.mayoclinic.org/discussion/unknown-cause-or-idiopathic-sfn/
Small Fiber Neuropathy: https://connect.mayoclinic.org/discussion/small-fiber-neuropathy-1/
Curious: Are you the only family member with SFN?: https://connect.mayoclinic.org/discussion/curious-are-you-the-only-family-member-with-sfn/

The Neuropathy Commons website has some information you might find helpful here -- Genetic Testing: Is It for Me?: https://neuropathycommons.org/genetics/genetic-testing-it-me

Were you diagnosed by a neurologist or by using a skin punch biopsy or other test?