HTT and Huntington disease: Remarkably, frozen samples of human postmortem brain of control and HD individuals could be separated by iodixanol (OptiPrep) to reveal a relative distribution of subcellular markers and of Huntingtin similar to that in mice, although the synaptic proteins PSD95 and SNAP 25 were separated to higher fractions (3–6) than in mice in both control and HD putamen.