@sunnyflower You're right that once a doctor is confident in a diagnosis that they wouldn't see further testing as necessary. The first neurologist I saw declined to do a nerve biopsy for me (although I understand it's standard with doctors in the US) because to him my diagnosis had already been confirmed by the QSART test.

For genetic testing I think it could make a difference in the diagnosis? If they identify a genetic link then maybe there's no need to turn over every stone looking for hidden autoimmune or neurological causes?