N-Acetylglucosamine-asparagine levels in tissues of patients with aspartylglycosaminuria.

The levels of the main glycoprotein-derived storage compound, N-acetylglucosamine-asparagine, in various post mortem tissues of three adult patients with inherited deficiency of lysosomal 1-aspartamido-beta-N-acetylglucosamine amidohydrolase (aspartylglycosaminuria) were measured by gas-liquid chromatography. All aspartylglycosaminuria tissues studied contained significant amounts of N-acetylglucosamine-asparagine, whereas none of the corresponding control tissues contained detectable amounts of this compound. High levels of N-acetylglucosamine-asparagine were found in the liver (3.65 mg/g wet weight), spleen (2.24) and thyroid (2.18), and lower levels in the kidney (0.89), brain (0.53), spinal cord (0.32), sciatic nerve (0.34) and skeletal muscle (0.16). The results show that N-acetylglucosamine-asparagine accumulates chiefly in tissues with important functions in glycoprotein metabolism and/or high endocytic activity. Correlation of the results to the clinical manifestations of aspartylglycosaminuria did not reveal a direct relationship between the amount of N-acetylglucosamine-asparagine stored and the degree of organ dysfunction.