An unusual case of mannosidosis with severe deficiency of acid mannosidase in leukocytes and high residual enzymatic activity in skin fibroblasts.

A case of mannosidosis with high residual activity of fibroblast acid mannosidase is described. The mutant enzyme was thermostable and has an almost normal Km value. The patient had mild clinical manifestations, but excretion of mannose-rich oligosaccharides was very high. This case of mannosidosis is compared with those reported in literature.