INFANTILE SIALIC-ACID STORAGE DISEASE - BIOCHEMICAL-STUDIES

Infantile free sialic acid storage disease (ISSD), is an inherited met abolic disorder characterized by hyperexcretion of free sialic acid in the urine and by its storage in the lysosomes of different tissues. I n order to obtain more reliable data on the amount of total and free s ialic acid, we analyzed the urine, brain, cerebellum, liver, spleen, a nd kidneys from a 3-month-old baby who died with a diagnosis of ISSD. The lysosomal nature of the disease was confirmed by an electron micro scopic study of cells in culture. No significant abnormalities were fo und involving cholesterol, total phospholipids, glycolipids, and gangl iosides in the tissues examined. However, differences in the tissue di stribution of individual glycolipids and gangliosides were observed. T he amount of free and total sialic acid was markedly increased, due to the storage of free sialic acid accompanied by its hyperexcretion in the urine. These results demonstrate and confirm that only acid monosa ccharide transport from the lysosome compartment is involved in the pa thogenesis of ISSD. (C) 1995 Wiley-Liss,Inc.