GRN and enthesitis: Despite the statistical significance of our results, however, the relative differences in the frequency of PGRN Abs between the various subgroups were rather small (PGRN Ab-positive enthesitis 21.3% vs. PGRN Ab-negative enthesitis 14.7% and PGRN Ab-positive dactilytis 21.8% vs. PGRN Ab-negative enthesitis 15.4%).