Hypermobility Type EDS is inherited in an autosomal dominant manner. In most cases, the causes of this type of Ehlers-Danlos Syndrome is unknown.

Mutations in one copy of the TNXB gene may be responsible for this condition in some people. The TNXB gene makes a protein called tenascin-X, which functions outside of cells and appears to interact with other proteins (such as collagen). It is not yet clear how mutations in this gene lead to clinical features of this disorder.