PRTN3 and rheumatoid arthritis: In line with the efforts to more adequately understand the progression of the immunopathogenic pathways along the disease course, a novel classification by stages has been recently suggested: triggering phase, with individuals genetically predisposed to RA exposed to diverse environmental triggers; maturation phase, in individuals without synovitis but positive for anticitrullinated protein antibodies (ACPA); targeting phase, in individuals seropositive for ACPA with arthralgia; and fulminant disease, characterized by established RA [18].