Lysosomal storage disease is a metabolic disorder arising from defects in lysosomal function. It results when the lysosome, which is an organelle found in the body's cells, malfunctions. The lysosome is the cell’s recycling center because it processes unwanted material into substances that the cell can utilize. Lysosomes break down this unwanted matter via enzymes, highly specialized proteins essential for survival. Lysosomal disorders are triggered when a particular enzyme exists in too small an amount or is missing altogether. Thus, when the lysosome doesn’t function normally, excess products destined for breakdown and recycling are stored in the cell.
Lysosomal storage disease belongs to a group of approximately 50 rare inherited metabolic disorders that result from defects in lysosomal function. The symptoms of lysosomal storage disease vary, depending on the particular disorder and other variables like the age of onset, and can be mild to severe. They can include developmental delay, movement disorders, seizures, dementia, deafness and/or blindness. Some people with Lysosomal storage disease have enlarged livers and enlarged spleens (splenomegaly), pulmonary and cardiac problems, and bones that grow abnormally. There are no cures for lysosomal storage diseases and treatment is mostly symptomatic, although bone marrow transplantation and enzyme replacement therapy (ERT) have been tried with some success.