Skeletal Dysplasias: An Overview.

Constitutional disorders of bone, commonly termed skeletal dysplasias (SDs), are inherited disorders of cartilage and/or bone that affect their growth, morphometry and integrity. Associated skeletal abnormalities are usually but not invariably symmetrical. They may be classified as osteochondrodysplasias, which are conditions associated with abnormalities of the growth (dysplasias) or texture (osteodystrophy) of bone and/or cartilage, or dysostoses, which are conditions secondary to abnormal blastogenesis (occurring at or around the 6th week of in utero life). Skeletal involvement may also occur in other multisystem hereditary and acquired syndromes. The 2010 Nosology and Classification of Genetic Skeletal Disorders listed 456 conditions, of which approximately 50 are perinatally lethal, and 316 are associated with one or more of 226 genes. When an SD is suspected, a standard series of radiographs, collectively known as a skeletal survey, should be performed. The diagnosis of individual conditions is highly dependent on radiographic pattern recognition, which is achieved through a systematic review of the images and enhanced by discussion with colleagues and through the use of available tools, such as atlases and digital databases. This article summarises a systematic approach to the diagnosis of SDs, demonstrated using examples of some of the more common lethal and non-lethal conditions.