MPO and systemic lupus erythematosus: Consequently, the RDwCNS group comprised 23 well-characterized patients, including 20 patients with connective tissue disease (18 with SLE and two with an undifferentiated connective tissue disease (UCTD)) and three patients with primary vasculitides (one MPO-associated MPA, one PR3-associated GPA, and one Behçet’s disease).