We observe that most of these drugs target a small subset of proteins or protein families directly related to the diseases, such as the growth hormone-releasing hormone receptor (GHRHR) for hypogonadism treatment, the somatostatin receptor (SSTR) for acromegaly treatment, and the DOPA decarboxylase to prevent dopamine formation in the treatment of Parkinson’s disease. This evidence concerns the gene DDC and Parkinson disease.