Heritable diseases of the skeleton. Part II: Molecular insights into skeletal development-matrix components and their homeostasis.

A range of osteochondrodysplasias is caused by mutations in components of the extracellular matrix in cartilage and bone and in molecules that are important for posttranslational processing of such components. Mutations in the genes encoding the two polypeptide subunits of collagen I cause defects in the structure of bone matrix while mutations in genes encoding cartilage-specific collagens are responsible for several chondrodysplasias. Abnormalities in cartilage structure and function can also be due to mutations in structural noncollagenous components such as aggrecan and cartilage oligomeric matrix protein. Finally, several cartilage and bone disorders are due to abnormalities in sulfate transport and regulation of bone matrix homeostasis.