Volume 36, Issue 4

Monogenic Ehlers-Danlos syndromes (EDS) are a group of inherited connective tissue conditions that are clinically characterised by joint hypermobility, skin hyperextensibility and/or fragility, and generalised tissue fragility. Gene panel testing with massively parallel sequencing is currently gold standard to confirm diagnoses of the monogenic EDS types. We aim to report on the (combination of) clinical features of the monogenic EDS types through text and photographs, to aid clinical diagnosis as despite the significant progress in genetic testing possibilities, a thorough clinical assessment which includes medical history, family history and physical examination remains important in the diagnostic process. In addition, in those cases where no molecular diagnosis is possible, a clinical diagnosis can still guide management and surveillance.

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.

With increased application of Next Generation Sequencing (NGS) in the diagnosis of monogenic Ehlers-Danlos syndromes, there is an increased probability to identify variants of unknown significance. Additionally, in some cases no genetic alteration may be identified whilst there is a strong clinical suspicion on a monogenic EDS type. The diagnostic value of non-genetic investigations, which prior to NGS were quite commonly used to support the clinical diagnosis of monogenic EDS types, is explored. In addition, new structural/functional investigations that could deliver evidence towards pathogenicity are discussed. It appears that certain functional and/or structural investigations used frequently in the past can remain helpful and can provide additional evidence that may confirm a clinical diagnosis of a monogenic EDS type. However, there is a need for the development of novel structural/functional studies for monogenic types of EDS. The level of evidence of such studies for application in the established diagnostic DNA variant classification criteria remains to be determined.

The monogenic Ehlers – Danlos syndromes (EDS) constitute a clinically and genetically heterogenous group of connective tissue disorders with overlapping features of generalized joint hypermobility, skin hyperextensibility and tissue fragility. Vascular complications can be observed in several EDS types, but generalized tissue fragility resulting in significant increased risk on vascular events from a young age are a major clinical characteristic of vascular Ehlers – Danlos (vEDS, former Type IV). This is a rare, monogenic EDS type, with a suspected prevalence of 1:50 000. Even though progress regarding awareness and management of vEDS has been made, further studies are needed regarding optimal treatment and follow up. In this manuscript we present the perspective of a vascular surgeon regarding the current literature to management and treatment options for vascular complications in vEDS.