Most of the subjects with ScAb-ILD matched the diagnostic criteria for IPAF because these patients have a serologic domain (anti-centromere, anti-scleroderma-70, and anti-U1 RNP antibodies) and morphologic domain as indicated predominantly by radiological findings of NSIP, intrinsic airway disease with bronchial wall thickening and air trapping, and pathological findings, and by cellular infiltration of the airway and organizing pneumonia. Here, U1 is linked to interstitial lung disease.