PD is associated with degeneration of nigrostriatal dopamine (DA) neurons; however, PPN cholinergic, glutamatergic, substance P, GABAergic, and glycinergic neurons also degenerate in PD (Hirsch et al., 1987; Jellinger, 1988; Gomez-Gallego et al., 2006; Rinne et al., 2008; Pienaar and van de Berg, 2013). This evidence concerns the gene TAC1 and Parkinson disease.