GM1 is one of a group of diseases called "lysosomal storage diseases". There are about 50 known lysosomal storage diseases, all of which are genetic and result from defects in the lysosomes of cells. In the case of GM1, genetic mutations lower the level of ßgalactosidase (ß-gal) activity in the body - an enzyme needed to break down GM1 ganglioside and keratan sulfate within the lysosomes. Low levels of ß-gal cause waste products to accumulate. Neurons, or cells that transmit information within the nervous system, are particularly affected