Abstract
Achondrogenesis II is an inherited disorder of endochondral bone growth characterized clinically by severe (lethal) dwarfism and pathologically by the production of reduced amounts of cartilage matrix. To further define its pathogenesis, we studied growth plate tissue from 4 patients by a combination of microscopic and biochemical methods. Immunostaining of undecalificied Spurr embedded sections with a battery of collagen antibodies revealed that the major collagen of the resting cartilage matrix was type I rather than the expected type II (cartilage) collagen which was much reduced in amount. Analysis of resting cartilage collagens by SDS-PAGE and size exclusion HPLC mapping of cyanogen bromide peptides confirmed that collagen I was the major collagen and failed to detect collagen II. The results suggest at least two possibilities. First, there may be a defect in the structural gene for collagen II which interferes with the synthesis and/or secretion of the protein in an analagous fashion to that which occurs for collagen I in the osteogenesis imperfecta syndromes. Alternatively, the secretion of collagen I may reflect prematurity and/or abnormal regulation of the normal “switch” from collagen II to collagen I synthesis that occurs during later stages of growth plate chondrocyte differentiation. In any event the observations indicate that growth plate collagen production is disturbed in the disorder.
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Horton, W., Machado, M., Chou, J. et al. 828 ABNORMAL CARTILAGE COLLAGENS IN ACHONDROGENESIS II. Pediatr Res 19, 248 (1985). https://doi.org/10.1203/00006450-198504000-00858
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DOI: https://doi.org/10.1203/00006450-198504000-00858