Finally, 13 pSS-ILD patients were excluded because they presented overlap with a second connective tissue disease (namely scleroderma in three cases, SLE in 2 cases, rheumatoid arthritis in two cases, anti-synthetase syndrome in four cases, mixed connective tissue disease in one case and ANCA-MPO vasculitis in 1 case). This evidence concerns the gene MPO and mixed connective tissue disease.