PRTN3 and rheumatoid arthritis: Other biomarkers, such as miRNA (Cunningham et al., 2021), calprotectin (Jarlborg et al., 2020), anti-RA33 (Syed Mohamed Suhail et al., 2019), and anti-carbamylated protein (anti-CarP) antibodies (Lamacchia et al., 2021), may be effective in the diagnosis of early RA, but these markers are not widely accepted in clinical application, and their prognostic significance remains controversial owing to the lower sensitivity and specificity of supplementary diagnosis compared with RF and ACPA.