Ehlers Danlos syndrome is a group of heritable disorders of the connective tissue characterized by hyperextensible skin, joint hypermobility, and abnormalities of the internal organs. Most of these abnormalities result from defects in the structure or function of the collagen protein. Various forms of EDS are known. The spondylodysplastic type is a relatively rare subtype of EDS, which is principally characterized by a progeroid facies, multiple nevi, mild mental retardation, skin hyperextensibility, bruisability, moderate skin fragility, and joint hypermobility noticed principally in the digits.
Mutations in the B4GALT7 (Xylosylprotein 4-Beta-Galactosyltransferase, Polypeptide 7) gene have been shown to be responsible for the progeroid form of EDS. This gene codes for a membrane bound glycoprotein, galactosyltransferase-I, which plays a major role in the formation of proteoglycans. Since proteoglycans form an essential part of the extracellular matrix, and play major roles in several developmental and metabolic processes, it is easy to see how defects in its synthesis could lead to defects in the musculoskeletal system.