Genetic diagnosis of the Ehlers-Danlos syndromes.

The Ehlers-Danlos syndromes (EDS) represent a group of genetically diverse disorders characterized by the variable combination of joint hypermobility, hyperextensibility of the skin, and connective tissue fragility affecting the skin and other organs. Based on clinical features, 13 different types of EDS have been delineated, 12 of which represent monogenic conditions caused by pathogenic variants in 21 confirmed genes. Pathogenesis is related to disturbances of collagen formation and/or stability. No monogenic cause has been identified for hypermobile EDS (hEDS), a more common EDS type, which is unlikely to represent a single gene disorder in the majority of affected individuals and at present cannot be diagnosed by genetic investigations. Here we summarize the clinical features and the molecular bases of the monogenic EDS types, highlight diagnostic challenges, and provide guidance for the molecular work-up of affected individuals. In general, genetic tests are indicated if clinical features suggest a monogenic EDS type but are usually unrewarding for other cases of hypermobility.