Urinary Glycosaminoglycan Electrophoresis With Optimized Keratan Sulfate Separation Using Peltier System for the Screening of Mucopolysaccharidoses

Abstract

The purpose of this communication is to indicate a simple and rapid method with a small volume of urine sample to detect urine glycosaminoglycan (GAG) and serve as a screening procedure for mucopolysaccharidoses (MPSs). Total GAG measurement for patients with MPS disorders is considered to be the first step in diagnosis of those heterogeneous group of lysosomal storage disorders presenting clinical phenotype. In this study, modified 9-dimethylmethylene blue method is used for total GAG measurement. Following GAG quantitation, the procedure described here allows GAG isolation from a very a small volume of urine sample and subjected to high-resolution GAG electrophoresis, which can be easily performed in routine clinical diagnostic laboratories. Glycosaminoglycan precipitation is a modified method based on total GAG concentration in the urine. For optimized isolation of total GAG for electrophoresis, instead of considering the urine creatinine concentration, 300 μg/mL GAG containing urine is considered to be the target concentration for the best precipitation with 1000 μL cetylpyridinium chloride (CPC)/citrate buffer. Glycosaminoglycan concentration-based precipitation of urine with CPC allows the laboratory to be able to work with a small volume of urine sample by keeping the precipitating ratio with CPC constant for samples that contain GAG less than 300 μg/mL. Based on the effect of cold buffer using low voltage, GAGs high-resolution electrophoresis banding patterns described here enable a clear separation of keratan sulfate from chondroitin sulfate as well as dermatan sulfate (DS1 and DS2) and heparan sulfate. By this procedure, GAG patterns are more clear, easily identified, and provide a guide for the enzyme analysis deficient in the MPS disorders.