An update on the new classification of Ehlers-Danlos syndrome and review of the causes of bleeding in this population

It has long been hypothesized that bleeding symptoms in people with hypermobility occur as a result of abnormalities in the collagen of the vessel wall or the connective tissues. The bleeding symptoms, particularly in the skin, have been attributed to the fragility of skin and blood vessels caused by "defective collagen wickerwork" of the reticular layer of the skin. Collagen, which forms the framework of vessel walls, is altered in many patients with Ehlers-Danlos syndrome (EDS) leading to weakening of the vessel wall or the supporting tissues. Another important function of subendothelial collagen is its interaction with platelets and von Willebrand factor, which results in the propagation of a platelet plug. Thus, abnormalities in subendothelial collagen may alter its interaction with platelets and VWF. More recently, hypermobile-EDS (hEDS) has been associated with mast cell disorders, a condition independently associated with bleeding symptoms. It has also been observed that patients with mild bleeding disorders have a more severe bleeding phenotype when they have co-existing joint hypermobility.