At the time of IPF diagnosis or during follow-up, up to 20% of patients present with ANCA positivity, without clinical manifestations of systemic vasculitis.[9–12] The most frequently detected ANCAs are anti-MPO and much less often antiproteinase antibodies , antielastase, antilactoferrin, or nonspecific ANCA positivity. The gene discussed is MPO; the disease is necrotizing vasculitis.