Quantitative determination of 4-N-2-acetamido-2-deoxy-beta-D-glucopyranosyl-L-asparagine in the urine of patients with aspartylglycosaminuria by gas-liquid chromatography.

A specific and sensitive method for the quantitative ;determination of glcNAc-Asn in the urine of patients with inherited deficiency of the lysosomal hydrolase N-aspartyl-beta-glucosaminidase is reported. The method is based on GLC assay of GlcNAc-Asn as its methylated derivative and requires 100 microliter of urine. The mean urinary excretion of GlcNAc-Asn in 14 AGU patients was 0.99 mmol/24 hr (range 0.15 to 1.88). Young patients had similar urinary levels of GlcNAc-Asn to those of the older ones when the results were calculated on the basis of creatinine excretion. Mass fragmentographic analysis revealed the presence of minimal amounts of GlcNAc-Asn in normal urine also. In four of the eight normal subjects studied, a rough quantitative estimation was feasible; the urinary output of GlcNAc-Asn in these subjects ranged from approximately 0.001 to 0.01 mmol/24 hr.