COMP and disease of the tendon: We have previously shown that COMP is expressed in skeletal muscle, Achilles and patellar tendon and spinal ligament of mice at different ages and that mild myopathy associated with a CTD-COMP mutation is due to an underlying tendinopathy [25] and hypothesised that this pathological feature was most likely due to the role that COMP plays as a catalyst in collagen fibrillogenesis [16,25].