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.