Mucolipidosis III: two patients displaying genetic pleiotropism.

Two Cape Coloured siblings with typical features of Hurler's syndrome, but without mucopolysacchariduria or mucopolysaccharide accumulation in tissues, are presented. The clinical features, in conjunction with raised beta-D-galactosidase and alpha-L-fucosidase levels in fibroblast cultures from one of the patients, suggest the diagnosis of a mucolipidosis. Theories relating to the intracellular deficiency and extracellular excess of lysosomal enzymes in these conditions are reviewed. Phenotypical and cell culture differences between 2 siblings who display the same overall clinical syndrome, illustrate the genetic pleiotropism inherent in this group of diseases.