Features of I-Cell Disease in Normal Tissues

To the Editor: I-cell disease, a fatal neurodegenerative disorder of childhood with autosomal recessive inheritance,^1,2 clinically resembles the mucopolysaccharidoses, but urinary excretion of mucopolysaccharides is usually normal. Characteristic cytoplasmic inclusions are found in cultured skin fibroblasts and peripheral lymphocytes from patients with the disease. Concentrations of lysosomal hydrolases are decreased in the cultured skin fibroblasts, while correspondingly increased in the culture medium.^3,4 The actual gene defect in the disorder and its relation to the characteristic abnormal excretion of enzymes is yet to be elucidated. In addition to an abnormally slow electrophoretic mobility of I-cell disease fibroblast intracellular β-hexosaminidase⁵ there.