The application of gel filtration and specific analyses of urinary carbohydrate and protein material to the diagnosis of metabolic disorders

Abstract

A gel filtration method developed for urinary carbohydrate and proteinaceous material based on Bio-Gel P-2 cross-linked polyacrylamide gel has been coupled to specific continuous automated analyses for neutral and acidic carbohydrate and protein. The multichannel analytical system has been applied to urine from normal subjects and from known cases of genetic hyperglycosaminoglycanuria (“mucopolysaccharidosis”) to analyse not only the non-dialysable, high molecular weight material but also the low molecular weight material which comprises over 90% of urine solutes in many cases. Urine from affected patients was easily distinguished from that from normal subjects and the method also differentiated between various syndromes. For the Morquio syndrome with mucopolysacchariduria and Scheie syndrome the ratio of acidic to neutral carbohydrate (carbazole : cysteine ratio) in the high molecular weight material is the lowest (less than 0.6) whilst for the Hunter syndrome the value is greater than 2.0, with values for Hunter and Sanfilippo syndromes being intermediate. The ratio of high to low molecular weight material for the Morquio syndrome with mucopolysacchariduria in the case of the borate-carbazole assay is lower (below 0.2) but in the case of the L-cysteinesulphuric acid assay is higher (above 0.6) than values obtained for the other syndromes. There was evidence for a division within the Sanfilippo syndrome using this molecular size ratio for the L-cysteine-sulphuric acid assay, some with values greater than 0.5 and some with values below 0.3. In urine from cases of Morquio syndrome with mucopolysacchariduria there was also evidence of large amounts of intermediate molecular weight material. The application of this method to studies of other disorders of inherited metabolism is equally possible and is discussed.