These genes, which include the PD-related gene SNCA, are associated with GO classes that indicate processes relevant to neuronal function (for example, GO:0042982, amyloid precursor protein metabolic process; GO:0014069, postsynaptic density; GO:0030424, axon; GO:0042417, dopamine metabolic process; GO:0030517, negative regulation of axon extension; GO:0050804, modulation of chemical synaptic transmission) (Supplementary Table 9). Here, APP is linked to Parkinson disease.