During cartilage morphogenesis, differentiating chondrocytes secrete extensive ECM defined early in resting and proliferating chondrocytes by the expression of col2a1 and defects in the composition or integrity of the ECM cause well-known skeletal diseases/dysplasias (Krakow, 2015; Krakow and Rimoin, 2010). The gene discussed is COL2A1; the disease is bone disorder.