Gene expression profiling of peripheral blood cells in arthralgia patients (with confirmed absence of synovitis) and ACPA positivity highlighted a gene signature, including interferon (IFN)-mediated immunity and cytokine/chemokine activity that were specifically observed in at-risk individuals who then went on to develop arthritis.69 A second signature, including increased expression of B-cell-specific genes, appeared to be associated with protection from arthritis development. Here, PRTN3 is linked to arthritic joint disease.