Abnormal dermal proteoglycan in aspartylglycosaminuria: a possible mechanism for ultrastructural changes of collagen fibrils in a glycoprotein storage disorder.

Changes in the structure and organization of collagen fibrils were recently described in the skin of aspartylglycosaminuria patients. The skin of the patients contained a normal amount and distribution of glycosaminoglycans, but the dermatan sulfate of aspartylglycosaminuria skin was more sensitive to chondroitinase AC digestion, resulting in unsaturated 4-sulfated disaccharides which were not detected in controls. Isolated dermatan sulfate chains as well as the chains present in the intact core protein synthesized by skin fibroblasts from an aspartylglycosaminuria patient were also digestible with chondroitinase AC, while those of a control fibroblast culture could be digested with chondroitinase ABC only. This is indirect evidence for abnormal epimerization of dermatan sulfate in the skin of aspartylglycosaminuria patients, which may be associated with the changes in collagen fibril formation.