Though dysfunctions of the dopaminergic system are involved in neurological disorders, such as Tourette’s syndrome [7], schizophrenia [8,9], pituitary tumors [10], PD [11,12,13,14,15], and DRD [4,5,16], the loss of nigrostriatal tyrosine hydroxylase (TH) protein is distinctive in PD and DRD. Here, TH is linked to Parkinson disease.