Mutations in Biosynthetic Enzymes for the Protein Linker Region of Chondroitin/Dermatan/Heparan Sulfate Cause Skeletal and Skin Dysplasias

Table 1

Biosynthetic enzymes of the GAG-linker region tetrasaccharide.

Enzymes; (activity)	Coding genes	Chromosomal location	MIM number	Human genetic disorders; (GAG linkeropathies)	Amino acid changes in disorders	References
Xylosyltransferase; (XylT)	XYLT1	16p12.3	608124; 615777	Desbuquois dysplasia type 2,; short stature syndrome	Pro93Alafs69; Arg147X; Arg481Trp; Arg598Cys; two mutations in splice site	[22, 23]
	XYLT2	17q21.33	608125	Spondyloocular syndrome with bone fragility, cataracts, and hearing defects	Ala174Profs35; Val232Glyfs54	[24]
4-Galactosyltransferase-I; (GalT-I)	B4GALT7	5q35.2-q35.3	130070; 604327	Ehlers-Danlos syndrome progeroid type 1,; Larsen of Reunion Island syndrome	Ala186Asp; Leu206Pro; Arg270Cys	[25–28]
3-Galactosyltransferase-II; (GalT-II)	B3GALT6	1p36.33	271640; 615349; 615291	Ehlers-Danlos syndrome progeroid type 2,; spondyloepimetaphyseal dysplasia with joint laxity type 1	Met1?; Arg6Trp; Ser65Gly; Pro67Leu; Ala108Glyfs163; Asp118Alafs160; Met139Ala141del; Asp156Asn; Arg197Alafs81; Asp207His; Gly217Ser; Arg232Cys; Cys300Ser; Ser309Thr	[29–31]
3-Glucuronyltransferase-I; (GlcAT-I)	B3GAT3	11q12.3	245600; 606374	Larsen-like syndrome B3GAT3 type; Multiple joint dislocations, a short stature, craniofacial dysmorphism, and congenital heart defects	Pro140Leu; Arg277Gln	[32–34]