Purpose or Case Report: Skeletal dysplasias encompass a heterogeneous group of over 400 disorders. They are individually rare, but collectively common with an approximate incidence of 1/5000; thus, radiologists occasionally encounter skeletal dysplasias in daily practice. However, many radiologists and trainees struggle with this topic because of the lack of proper resources.

A group of skeletal dysplasias that share similar radiological patterns has been grouped into a “skeletal dysplasia family” which generally have common pathogenesis. For example, a skeletal dysplasia family comprising mucopolysaccharidosis, oligosaccharidosis, and mucolipidosis all radiologically exhibit dysotosis multiplex, and all share an abnormality in lysosome dysfunction.

The beauty of this family concept is its simplicity and power. First, it allows a more systematic approach to the chaotic world of skeletal dysplasias – a stepwise approach, with the first step of general pattern recognition and categorization of a certain case into a certain family, and the second step of diagnosis based on more meticulous observations for subtle but distinctive radiological findings. Since major skeletal dysplasia families are limited in number, the radiologist can become familiar with their patterns. Second, radiographs can predict the presence of genetic mutations. Geneticists or pediatricians would appreciate the correct radiological diagnosis even in today’s genetics practice with advanced molecular techniques. Radiological diagnosis and genetics are complementary. Third, it may lead us to a more precise assessment of radiological findings. Shared findings among family members allow more accurate characterization of the severest end of the family which occasionally look similar to the one with different pathogenesis.

The purpose of this exhibit is to demonstrate the imaging characteristics of major skeletal dysplasia families and the stepwise approach to the diagnosis. We will review the classic and more recently established dysplasia families. In addition, we will review clinical and genetic features that help radiologists to participate in multidisciplinary care.

Introduction – Dysostosis multiplex family – FGFR3 (achondroplasia) family – COMP family – Type II collagenopathies – TRPV4 (metatropic dysplasia) family – Skeletal ribosomopathies – DTDST (diastrophic dysplasia) family – Linkeropathies – Filaminopathies A and B – Punctata group – Skeletal ciliopathies – Osteogenesis imperfecta group
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