Arylsulfatase B-deficient mucopolysaccharidosis in rats

N-acetylgalactosamine-4-sulfatase: identification of four new mutations within the conserved sulfatase region causing mucopolysaccharidosis type VI

Mucopolysaccharidosis type VI (MPS VI; Maroteaux-Lamy syndrome) is the lysosomal storage disorder resulting from the deficient activity of N-acetylgalactosamine-4-sulfatase (arylsulfatase B; ASB). MPS VI has been described in man, cats and rats, and several mutations in the ASB gene have been identified in human patients and the animal models. Notably, ASB belongs to a family of sulfatases which are highly conserved, suggesting that they are related evolutionarily and functionally. In this manuscript, four new mutations causing MPS VI are described within the human ASB gene. Each of these mutations occurred in or near the hexapeptide 144GKWHLG149, one of the most highly conserved 'sulfatase' regions. In fact, three of the mutations occurred within the same codon, W146. Thus, these results provide new insights into the molecular lesions causing MPS VI and highlight the importance of this conserved sulfatase region.

Growth plate pathology in feline mucopolysaccharidosis VI

The mucopolysaccharidoses (MPS) are a family of lysosomal storage diseases that result from the accumulation of partially catabolized glycosaminoglycans (GAGs) within lysosomes. A characteristic of most affected individuals is radiographic evidence of symmetrical epiphyseal dysplasia, with short stature and degenerative joint disease. Although there is evidence of epiphyseal dysfunction, little is known of the changes that occur at the morphological level. The growth plate of the femoral head was studied by light and electron microscopy in five cats with MPS VI (Maroteaux-Lamy syndrome, arylsulfatase B deficiency) and 12 normal cats. Compared with the normals, the MPS VI cat growth plates exhibited poorly organized proliferative zones, an almost total loss of column formation in the hypertrophic zone, an uneven chondro-osseous junction, a disorganized calcifying cartilage zone, and abnormal or reduced numbers of osteoclasts. By electron microscopy, the cytoplasm of affected cat chondrocytes was filled with membrane-bound vacuoles. Together these findings indicate that the MPS diseases cause major changes in growth plate structure and function.

Pathological characteristics of mucopolysaccharidosis VI in the rat

The histological and electron microscopical characteristics of the pathology of rats with arylsulphatase B-deficient mucopolysaccharidosis (mucopolysaccharidosis VI; MPS VI) were investigated. In affected animals, intracytoplasmic vacuoles were prominent in chondrocytes, the macrophage system, cardiac valve fibroblasts, cornea, connective tissues, vascular smooth muscle cells and uterine stromal cells. Tissues containing glucosaminoglycans stored in lysosomes were positive to Mowry's colloidal iron and alcian blue stains. By electron microscopy, the lysosomes were seen to be distended by electron lucent or fine fibrillary storage material, and lysosomal storage was also detected in the endothelial cells of the arteries and cornea. In the central and peripheral nervous system abnormalities were restricted to the connective tissue. Lesions in the affected rats resembled those described in human and feline mucopolysaccharidosis VI. These results indicate that MPS VI of the rat may be a useful animal model for human MPS VI (Maroteaux-Lamy syndrome).