The underlying diseases of patients in the AFOP group were as follows (Table 1): 19 had COP, 4 had autoimmune diseases (2 anti-neutrophil cytoplasmic antigen [ANCA]-associated vasculitis, 1 rheumatoid arthritis, and 1 anti-MDA5 antibody-positive polymyositis/dermatomyositis [PM/DM]), 3 had chronic eosinophilic pneumonia (CEP), 3 had radiation pneumonitis, 2 had drug-induced pneumonia (afatinib and pembrolizumab), 2 had myelodysplastic syndrome (MDS), and 1 had IgG4-related disease. This evidence concerns the gene IFIH1 and immunoglobulin G4-related sclerosing disease.