Beta 1,4 galactosyltransferase 7 (B4GALT7) adds galactose (Gal) to beta-xyloside in a beta-1,4-linkage creating the second unit in the tetrasaccharide linker sequence in proteoglycans, the precursor required for extension of glycosaminoglycan (GAG) chains (Almeida et al. 1999). Defects in B4GALT7 does not transfer Gal to the xylosyl-unit and therefore the tetrasaccharide linker sequence necessary for extension of the GAG chain cannot be completed, affecting GAG synthesis and causing Ehlers Danlos syndrome progeroid type (EDSP) (MIM:130070) (Okajima et al. 1999, Miyake et al. 2014). Mutations causing EDSP are A186D, L206P and R270C (Okajima et al. 1999, Almeida et al. 1999, Bui et al. 2010, Faiyaz-Ul-Haque et al. 2004).