Among the AAV subsets, ILD was predominantly observed in MPA and MPO-AAV as compared with GPA and PR3-AAV [3]; however, significantly higher complication rate of ILD in the Japanese than in the European population is also observed when only MPA patients were compared [4], suggesting that genetic factors may contribute to the susceptibility to AAV-ILD. Here, MPO is linked to granulomatosis with polyangiitis.