A previous study by our group, which explored the frequency of specific immune cell subtypes in the peripheral blood of drug-naïve patients with PD, found decreased effector CD8+ T cells and NK cells with reduced cytotoxicity, which were associated with age, unified Parkinson’s disease rating scale (UPDRS) scores, and mini-mental state examination (MMSE) scores11. Here, CD8A is linked to Parkinson disease.