Mucopolysaccharidoses, Unclassified Types

A number sign (#) is used with this entry because of the uncertainty as to the distinctness from entities listed elsewhere, the likelihood that more than one gene is involved, and in general the obscure nature of the disorders discussed.

Special studies such as those by the methods of Neufeld reveal heterogeneity within several of the main types of mucopolysaccharidosis but some forms remain unclassified. For example, Horton and Schimke (1970) described brother and sister, aged 13 and 11, with features like pseudo-Hurler polydystrophy (mucolipidosis III) but with mucopolysaccharides (both chondroitin sulfate B and heparitin sulfate) in the urine in amounts about 10 to 15 times normal. Intelligence was normal. These patients were subsequently shown to have alpha-iduronidase deficiency. The clinical phenotype suggests the Hurler-Scheie compound. Valvular heart disease has been a problem in both sibs, who presumably have the Scheie syndrome (Horton, 1980). Brown and Kuwabara (1970) observed 2 sisters, aged 5 and 13 years, with Hurler-like facies, swollen fingers, dwarfed stature, severe progressive joint destruction and peculiar progressive peripheral annular corneal opacification. The parents were Puerto Rican first cousins. Fibroblasts showed metachromasia and increased mucopolysaccharide. Urinary mucopolysaccharide was normal. High doses of vitamins seemed to be beneficial. Scott et al. (1973) described a male child who had mucopolysacchariduria, mental retardation, 'dysostosis multiplex' and appearance similar to that of a mucopolysaccharidosis. Death occurred at 47 months from pneumonia. The reticuloendothelial system remained free of mucopolysaccharide although accumulations were found in the perichondrium, coronary arteries, aorta, and glomerular epithelial cells of the kidney. Lipid accumulated in peripheral neurons but not in central neurons.