Keep in mind when you see things posted on a public website (like Mayo) where it says “it is not useful to test for RNP without a positive ANA”. They are trying to say: in general, it is not the best idea to order this test for everyone if you have a negative ANA. But clinically… there actually might be people out there that have these rare results with discrepancies! Or their specialist feels there is a specific reason to do a certain test. That message is for the 95% or so of people who will probably not need an RNP antibody test after a negative ANA.