Systematic Approach to Skeletal Dysplasias with Emphasis on Non-lethal Disorders

Abstract

Dysplasias are defects arising during the prenatal stage of development that continue expression in postnatal life and may be primary or secondary. Primary skeletal dysplasias result from mutated genes and are expressed in mesenchymal tissues. Secondary dysplasias result from extraosseous factors causing developmental abnormalities of the skeletal system. As knowledge of clinical medicine, molecular biology, and genetics advance, the number of known skeletal dysplasias has been growing by leaps and bounds. Radiology plays a major role in caring for these patients. This chapter provides an overview of the more common and/or more interesting skeletal dysplasias that a radiologist may encounter in practice, emphasizing the non-lethal disorders. The latest nosology and classification of skeletal dysplasias was introduced in 2006 comprising 37 groups and each group has between 2 and 23 entities. This classification is the basis of our presentation. However, various entities are discussed in alphabetical order to make it easier for the readers to refer to specific disorders. Achondroplasia is the most common non-lethal skeletal dysplasia and the most common lethal entity is thanatophoric dysplasia. Four categories of helpful hints are described to make learning and remembering skeletal dysplasias easier for the readers.