The presence of ACPAs also coincides in most cases with the presence of rheumatoid factors (RF) at diagnosis and the disease subset positive for either ACPA or RF, or both, is nowadays conventionally labeled as “seropositive RA.” Notably, in the risk phase there seem to be a higher proportion of ACPA positive individuals that are RF negative. This evidence concerns the gene PRTN3 and rheumatoid arthritis.