Ganglioside G is an acidic glycosphingolipid that contains two sialic acid residues linked to an inner galactose unit. It is a component of plasma membranes where it packs densely with cholesterol to form lipid microdomains that modulate both intra- and intercellular signaling events. The concentration of ganglioside G in human brain increases with age, constituting 7.85% of total sialic acid in the brain of 0- to 10-year-old subjects and 20.29% in 11- to 30-year-old subjects. Ganglioside G levels are positively correlated with pilocytic astrocytoma tumor grade, and G has been detected in various other gliomas, including primitive neuroectodermal tumors, glioblastomas, and anaplastic astrocytomas. Ganglioside G mixture contains ganglioside G molecular species with C18:1 and C20:1 fatty acyl chains.