Proteoglycans and glycosaminoglycans of human achondroplastic cartilage.

To determine whether proteoglycans or glycosaminoglycans from human achondroplastic cartilage are structurally abnormal, we isolated and characterized proteoglycans and glycosaminoglycans from fibular growth plates and from cartilage of the iliac crests of patients with achondroplasia. The glycosaminoglycans of both achondroplastic fibular growth plates and achondroplastic iliac-crest cartilage showed no differences from those isolated from normal tissues. Proteoglycans of achondroplastic iliac-crest cartilage were indistinguishable from those of controls. However, the proteoglycans of achondroplastic fibular growth plates showed higher proportions of proteoglycan aggregates, lower proportions of free proteoglycan monomers, higher intrinsic viscosities, and higher protein contents than those of age and sex-matched controls. The biochemical defect in achondroplasia does not involve an abnormality in the structure or formation of proteoglycan aggregates by proliferating chondrocytes, but appears to be related to abnormalities in chondrocyte proliferation and in the formation of a fully developed hypertrophic zone.