MGP and Keutel syndrome: Additionally, since MGP is presented by proliferative and late hypertrophic chondrocytes,29 its mutation is responsible for occurring of Keutel syndrome in patients exposing to abnormal cartilage calcification.30 The studies which carried out on mice with MGP deficiency showed that MGP acts as an inhibitor of extracellular matrix calcification on the epiphyseal growth plate.31 According to these evidences, as an inhibitor of extracellular matrix calcification and a factor of cell survival and proliferation, vitamin K plays a predominant role in cartilage metabolism.