PRTN3 and interstitial lung disease: SSc and rheumatoid arthritis can overlap in 25% of patients, based on two French studies, and the authors confirmed that the presence and co-existence of rheumatoid factor (RF), anti-citrullinated proteins (ACPA), and anti-carbamylated protein (anti-CarP) antibodies predict a worse prognosis manifested in vascular progression, synovitis, tenosynovitis, digital ulcers (DU), and interstitial lung diseases (ILD) [25, 26].