Rheumatoid arthritis (RA) is an autoimmune disease mainly characterized by joint inflammation. It presents extra-articular manifestations, with the lungs one of the affected areas. Among these, damage to the pulmonary interstitium (Interstitial Lung Disease -ILD) has been linked to proteins involved in the inflammatory process and related to extracellular matrix deposition and lung fibrosis establishment. Peptidyl arginine deiminase enzymes (PAD), which carry out protein citrullination, play a role in this context. A genetic association analysis was conducted on genes encoding two PAD isoforms, PAD2 and PAD4. This analysis also included ancestry informative markers and protein level determination in samples from patients with rheumatoid arthritis, RA-associated ILD, and clinically healthy controls. Significant single nucleotide variations (SNV) and a haplotype were identified as susceptibility factors for ILD-RA development. Elevated levels of PAD4 were found in ILD-RA cases, while PADI2 showed an association with RA susceptibility. This document presents the data obtained from the conducted research, which has been published.