Of those with RA, two had low-titer ACPA (26 units and 31 units), and one had high-titer ACPA (>250 units). Of those with high-titer ACPA (≥239 units), only one patient was diagnosed with RA. For those not diagnosed with RA, follow-up was available for more than two years for all but one patient, with an average follow-up of 8.4 ± 5.8 years. Here, PRTN3 is linked to rheumatoid arthritis.