[The biochemistry of collagen and the locomotor apparatus. Hereditary diseases of connective tissue and rheumatologic diseases (part 2)].

In lathyrism, the toxic agent directly blocks the development of the transverse links in the collagen fibre, while in bovine dermatosparaxis there is a deficiency of procollagen peptidase. Of the many clinical forms of the Ehlers-Danlos syndrome, some are due to a deficiency of lysine oxidase, others to deficiency of lysine hydroxylase and still others to procollagen peptidase deficiency. The essential deficiency in Marfan's disease is still unknown, but that in homocystinuria causes blocking of the groups necessary to form the transverse links. In osteogenesis imperfecta, which is probably a heterogeneous group, there is deficient consolidation of the collagen fibrils, the cause of which is still unknown. One possibility is a quantitative imbalance between chains of different types. In scleroderma there is excessive synthesis of an apparently normal connective tissue; the cause of this is also still unknown.