Teleost CT was previously shown to have a high in vivo potency (Gydesen et al., 2016) as well as antiresorptive and chondroprotective properties in the treatment of experimental RA and OA (Karsdal et al., 2008; Sondergaard et al., 2012; Wen et al., 2016), yet little is known about the role of endogenous CT/CTR signaling in inflammatory joint diseases. This evidence concerns the gene CALCR and rheumatoid arthritis.