What are the genetic changes related to GM1 gangliosidosis ?
Mutations in the GLB1 gene cause GM1 gangliosidosis. The GLB1 gene provides instructions for making an enzyme called beta-galactosidase (-galactosidase), which plays a critical role in the brain. This enzyme is located in lysosomes, which are compartments within cells that break down and recycle different types of molecules. Within lysosomes, -galactosidase helps break down several molecules, including a substance called GM1 ganglioside. GM1 ganglioside is important for normal functioning of nerve cells in the brain.  Mutations in the GLB1 gene reduce or eliminate the activity of -galactosidase. Without enough functional -galactosidase, GM1 ganglioside cannot be broken down when it is no longer needed. As a result, this substance accumulates to toxic levels in many tissues and organs, particularly in the brain. Progressive damage caused by the buildup of GM1 ganglioside leads to the destruction of nerve cells in the brain, causing many of the signs and symptoms of GM1 gangliosidosis. In general, the severity of GM1 gangliosidosis is related to the level of -galactosidase activity. Individuals with higher enzyme activity levels usually have milder signs and symptoms than those with lower activity levels because they have less accumulation of GM1 ganglioside within the body.  Conditions such as GM1 gangliosidosis that cause molecules to build up inside the lysosomes are called lysosomal storage disorders.