Although pulmonary involvement is common across all AAV subtypes, ILD is observed more frequently in patients with MPO-ANCA-positive MPA, with a documented prevalence of up to 51% in this subgroup, compared to up to 23% in patients with GPA [15,21,22,23,24,25,26,27,28,29] and only 6.3% in those with EGPA [30]. The gene discussed is MPO; the disease is eosinophilic granulomatosis with polyangiitis.