Then, GO annotation analysis showed that CD8+ T cell feature genes are primarily enriched in signal transduction (GO0007165), translation (GO0006412), immune response (GO0006955), apoptotic process (GO0006915) and inflammatory response (GO0006954) (Fig. 2D), while KEGG enrichment analysis found that CD8+ T cell feature genes are primarily enriched in Pathways of neurodegeneration (hsa05022), Amyotrophic lateral sclerosis (hsa05014), Prion disease (hsa05020), and Parkinson disease (hsa05012) (Fig. 2E). This evidence concerns the gene CD8A and Parkinson disease.