Enhanced serum COMP levels have been reported in different joint diseases, like osteoarthritis (Petersson et al., 1998; Clark et al., 1999), rheumatoid arthritis (Lindqvist et al., 2005; Wisłowska and Jabłońska, 2005), and knee injuries (Dahlberg et al., 1994), but also in response to physical activity (Pruksakorn et al., 2013; Cattano et al., 2017; Roberts et al., 2018). The gene discussed is COMP; the disease is osteoarthritis.