SLC17A6 and Huntington disease: Consistent with the selective vulnerability of corticostriatal synapses, immunoblot analysis of two rare samples of caudate nucleus from premanifest HD patients also showed reductions in levels of corticostriatal marker VGLUT1 and postsynaptic marker PSD95 but not thalamostriatal marker VGLUT2 (Extended Data Fig. 2l), further suggesting selective vulnerability of the corticostriatal connection in HD.