Human Genetic Disorders and Knockout Mice Deficient in Glycosaminoglycan

Table 2

Biosynthetic enzymes of the GAG-linkage region tetrasaccharide.

Enzymes; (activity)	Coding genes; (synonym)	Chromosomal location	mRNA accession number	MIM number	Human genetic disorders	Clinical features	References for the human diseases	References for the knockout mice
Xylosyltransferase; (XylT)	XYLT1	16p12.3	NM_022166	608124	Desbuquois dysplasia type 2, Short stature syndrome	Short stature, joint laxity, advanced carpal ossification, and hand anomalies.	[56–58]	[59]
	XYLT2	17q21.33	NM_022167	608125	—	—	—	[60]
𝛽4-Galactosyltransferase-I; (GalT-I)	B4GALT7	5q35.2-q35.3	NM_007255	130070; 604327	Ehlers-Danlos syndrome progeroid type 1; Larsen of Reunion Island syndrome	Developmental delay, aged appearance, short stature, craniofacial dysmorphism, and generalized osteopenia.; Multiple dislocations, hyperlaxity, dwarfism, and distinctive facial features.	[61–69]	—
𝛽3-Galactosyltransferase-II; (GalT-II)	B3GALT6	1p36.33	NM_080605	271640; 615349; 615291	Ehlers-Danlos syndrome progeroid type 2; Spondyloepimetaphyseal dysplasia with joint laxity type 1	Sparse hair, wrinkled skin, defective wound healing with atrophic scars, osteopenia, and radial head dislocation.; Spatulate finger with short nail, hip dislocation, elbow contracture, clubfeet, and mild craniofacial dysmorphism including prominent eye, blue sclera, long upper lip, and small mandible with cleft palate.	[70–72]	—
𝛽3-Glucuronyltransferase-I; (GlcAT-I)	B3GAT3	11q12.3	NM_012200	245600; 606374	Larsen-like syndrome B3GAT3 type; Multiple joint dislocations, short stature, craniofacial dysmorphism, and congenital heart defects	Joint dislocations mainly affecting the elbow, congenital heart defects such as bicuspid aortic valve, aortic root dilatation.	[73, 74]	[75, 76]
Xylose 2-O-kinase	FAM20B; (GXK1)	1q25	NM_014864	611063	—	—	—	—
Xylose 2-O-phosphatase	ACPL2; (XYLP)	3q23	NM_152282	—	—	—	—	—

—, not reported.
B4GALT7: xylosylprotein beta 1,4-galactosyltransferase 7; B3GALT6, beta 1,3-galactosyltransferase 6; B3GAT3, beta 1,3-glucuronyltransferase 3; FAM20B, Family with sequence similarity 20 member B; ACPL2, acid phosphatase-like 2.