The Chondrodystrophies

Abstract

The chondrodystrophies (osteochondrodysplasias) are a heterogeneous group of disorders which result in disproportionate short stature. Although they have long been considered to be generalized disorders of endochondral ossification, the extent of their heterogeneity has only recently been recognized and little is known concerning their pathogenesis. Prior to the past decade, most disproportionate dwarfs were referred to as having either achondroplasia (i.e., those with short limbs) or Morquio’s disease (i.e., those with short trunks). Thus in reviewing older series of cases of disproportionate dwarfism, the true diagnosis must be questioned unless clinical and radiographic data can be evaluated. For example, in Morch’s large series of “achondroplasts” published in 1941, on which the frequently used estimates of the mutation rate of achondroplasia were based, a whole host of different disorders were represented, including pseudoachondroplasia, hypochondroplasia, spondyloepiphyseal dysplasia, and multiple epiphyseal dysplasia.^223,288 Similarly, the great majority of early reports on the pathology of achondroplasia were based on autopsies of children now known to have thanatophoric dwarfism, achondrogenesis, or metatropic dwarfism.^{59,106,143,189,201,236}