B3GALT4 and Parkinson disease: Currently, the precise role of alterations in ganglioside expression in the degeneration of DAergic neurons in PD is not known, nor is it entirely clear why there is decreased expression of B3GALT4 and ST3GAL2 mRNAs in remaining dopaminergic neurons in the PD SN and what this means for the health and survival of these neurons.