In PD, the cytotoxic attack of a robust CD8+ T cell infiltration might initiate and propagate neuronal death and synucleinopathy by secreting cytolytic enzymes (granzymes A, B, and K) and/or pro-inflammatory cytokines (IFN-γ) (Galiano-Landeira et al., 2020). Here, CD8A is linked to Parkinson disease.