COMP and pseudoachondroplasia: COMP is essential in chondrogenic growth plate development (DiCesare et al., 1995; Rock et al., 2010) and mutations in COMP are linked to the human skeletal disorders pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED) (Briggs et al., 1995; Hecht et al., 1995).