For example, among target genes enriched onto serotonergic synapse pathway, 5-hydroxytryptamine receptor 2A (5-HT2A), 5-hydroxytryptamine receptor 2C (5-HT2c), and 5-hydroxytryptamine receptor 6 (5-HT6) were reported to be related to AD (Wilkinson et al., 2014). This evidence concerns the gene HTR2C and Alzheimer disease.