Detection of aspartylglycosaminuria by gas--liquid chromatography

I describe a rapid gas-chromatographic method for specific detection of the lysosomal storage disease aspartylglycosaminuria, based on the identification of the major storage compound, 2-acetamido-1-N-(4'-L-aspartyl)-2-deoxy-beta-D-glucopyranosylamine (GlcNAc-Asn) in the urine of affected individuals. A 50-microL sample of urine is methylated without prior purification; the methylation products are then analyzed by gas--liquid chromatography. Under these conditions a diagnostic GlcNAc-Asn peak can be seen in the urine of patients with aspartylglycosaminuria, but not in the urine of control subjects or patients with related storage diseases.