Ehlers-Danlos syndrome associated with glycosaminoglycan abnormalities.

Ehlers-Danlos syndrome (EDS) is a genetically and clinically heterogeneous group of connective tissue disorders that typically present with skin hyperextensibility, joint hypermobility, and tissue fragility. The major cause of EDS appears to be impaired biosynthesis and enzymatic modification of collagen. In this chapter, we discuss two types of EDS that are associated with proteoglycan abnormalities: the progeroid type of EDS and dermatan 4-O-sulfotransferase 1 (D4ST1)-deficient EDS. The progeroid type of EDS is caused by mutations in B4GALT7 or B3GALT6, both of which encode key enzymes that initiate glycosaminoglycan (GAG) synthesis. D4ST1-deficient EDS is caused by mutations in CHST14, which encodes an enzyme responsible for post-translational modification of GAG. The clinical and molecular characteristics of both types of EDS are described in this chapter.