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-β- 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.