CPA2 and Parkinson disease: In Table 2, we identified eight genes coding for olfactory receptors (ORs), such as OR10H1, OR52B6, and OR8S1. Moreover, genes that could be related to inflammation, myelination, immunity, ischemia, and cancer genes have been found, such as CPA2, AADACL3, GRAP2, and REST. The characterisation of these groups naturally leads to the emergence of a cluster composed of genes related to neurodegenerative diseases, such as Alzheimer’s and Parkinson’s diseases.