Lysosomal degradation pathway, defect

The attention of biochemists has been drawn to the importance of pathways of degradation of complex polysaccharides through the existence of at least 35 inherited lysosomal storage diseases 347-351 In many of these diseases one of the 40-odd lysosomal hydrolases is defective or absent. 

Sulfatide, which is particularly abundant in the white matter of the brain, is degraded by arylsulfatase A. This enzyme needs the assistance of a protein cofactor, SAP-B [18], Deficiency of this enzyme leads to metachromatic leukodystrophy, a disease which is due to sulfatide accumulation in various organs and which primarily affects the white matter of the brain [39]. Also the inherited deficiency of SAP-B leads to a lysosomal storage disease which resembles metachromatic leukodystrophy. However unlike typical metachromatic leukodystrophy not only sulfatide but also additional glycolipids, e.g. globotriaosylceramide, accumulate due to defects in several points of the pathway of GSL degradation [20]. 

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