These also exhibited differential gene expressions that are either previously known to be altered in human HD brains (such as the upregulation of the matrix metalloprotease gene MMP9 and downregulation of the BDNF receptor gene TRKB), or could be correlated with neuronal excitability and neuronal survival (such as upregulation of the α-synuclein gene (SNCA) and that encoding the pro-survival transcription factor SP9). This evidence concerns the gene SNCA and Huntington disease.