Lysosomal storage diseases (LSDs) are a group of over 50 genetically inherited disorders that are characterized by a deficiency of a vital enzyme. The lysosome is the cell's recycling center. When an enzyme does not function properly there is an accumulation of undigested material (substrate) inside the lysosome leading eventually to cell degeneration. This process results in accumulation of substrate in various tissues and organs of the body causing these organs to function less efficiently, resulting in progressive deterioration in physical and/or mental state, and eventually death.
Individual LSD's are classified as rare genetic disorders. However, when taken as a group, LSD's are far more common, with a prevalence rate of 1 per 7,700* births in some countries.
Lysosomal Enzyme Biology
In healthy cells, large molecules, such as glycolipids and glycogen, are broken down into functional units by lysosomal enzymes.
In lysosomal storage disorders, the cell is unable to produce an enzyme responsible for the breakdown of large molecules which leads to cell death.
* Meikle, PJ et al, Prevalence of Lysosomal Storage Disorders, JAMA 1999; 281:249-254