Gangliosidosis GM1 is a lysosomal storing disease. Lysosomes are small organelles in the cell where fats (lipids) and proteins are broken down. In GM1, a mutation in the GLB1 gene prevents sphingolipids from being properly processed, leading to lipid buildup and ultimately disruption of the cell's function.

Morphologically, this leads to severe vacuolization of virtually all lymphocytes.