The contribution of neutrophils to RA pathology can be seen inFelty’s syndrome (a severe form of RA) where the diagnostic findings includesplenomegaly, high neutrophil counts, and autoantibodies against PAD-4, an argininedeaminase that converts arginine to citrulline that bind to neutrophils and NETs(48). The gene discussed is PADI4; the disease is rheumatoid arthritis.