The skeletal dysplasias are a heterogeneous group of disorders which result in disproportionate short stature and/or skeletal deformities. Although they have long been considered to be generalized disorders of endochondral and/or membranous ossification, the extent of their heterogeneity has only recently been recognized and little is known concerning their pathogenesis. This project is directed toward a multidisciplinary investigation of the clinical, genetic, morphologic, biochemical and molecular characteristics of the skeletal dysplasias. The specific aims of this proposal will be: (a) expansion and further computerization of the International Skeletal Dysplasia Registry; (b) Definition of the clinical variability and genetic heterogeneity of the skeletal dysplasias; (c) definition of the natural history, growth characteristics and complications of each of these disorders and evaluation of methods for their treatment and management; (d) improvement of methods for their prenatal diagnosis; (e) clinical evaluation of medical and surgical methods of growth promotion; (f) elucidation of the histological, histochemical, immunocytochemical and ultrastructural characteristics of chondro-osseous tissue in each of these disorders; (g) elucidation of their basic biochemical defects by means of biochemical analysis of cartilage and cultured chondrocytes; (h) linkage analysis of individual syndromes with RFLP's of certain candidate genes; and (i) elucidation of their molecular defects by the analysis of collagen and proteoglycan mRNA and DNA. This program project is divided into a core facility - The International Skeletal Dysplasia Registry, plus five separate grant proposals: (1) Clinical and morphological studies; (2) Studies on differentiated chondrocytes in cultures; (3) Collagen biochemistry in the skeletal dysplasias; (4) Molecular studies in the skeletal dysplasias; (5) Analysis of proteoglycans in chondrodysplasias.