PRTN3 and rheumatoid arthritis: We found that only 10% of the patients had positive anti type 2 collagen autoantibodies; clustering RA patients based on the presence of Hps and Pg DNA (Figures 1A,B) and of antibodies specific for type 2 collagen (10% of the cohort, Supplementary Figure 1B), there were no significant differences in terms of disease severity, age at onset, and seropositivity, although Hps+ RA patients showed a trend of relatively low titers of ACPA, RF-IgM, and IgA.