SV2A can be found in all regions of the brain, particularly in subcortical regions such as the basal ganglia and thalamus, and studies have also reported that the density of SV2A can change in association with Alzheimer’s and Parkinson’s diseases, frontotemporal dementia, Huntington disease, epilepsy, schizophrenia, HIV infection, obesity, ischemic stroke, and normal aging [8,58]. The gene discussed is SV2A; the disease is obesity due to melanocortin 4 receptor deficiency.