This deuterated ganglioside is ideal for the identification of gangliosides in samples and biological systems using mass spectrometry.1 Gangliosides2 are acidic glycosphingolipids that form lipid rafts in the outer leaflet of the cell plasma membrane, especially in neuronal cells in the central nervous system.3 They participate in cellular proliferation, differentiation, adhesion, signal transduction, cell-to-cell interactions, tumorigenesis, and metastasis.4 GM2 regulates the function of ciliary neurotrophic factor receptors. The accumulation of GM2 (due to a deficiency in beta-hexosaminidase) has characterized Tay-Sachs disease (due to a mutation in the gene HEXA) and Sandhoff disease (due to a mutation in the gene HEXB). A mutation in the GM2A gene results in GM2 activator deficiency that also leads to accumulation of GM2.5