GSEA analysis further reveals that CD4-high-expressing samples are significantly enriched in the Parkinson’s disease pathway (NES = 1.57, p = 0.002) and oxidative phosphorylation (NES = 1.89, p = 7.41 × 10 − 6), indicating that mitochondrial energy metabolism dysregulation may drive PD progression through dual mechanisms: OXPHOS-Treg Axis Imbalance:T reg cells rely on oxidative phosphorylation (OXPHOS) to maintain immunosuppressive functions. This evidence concerns the gene CD4 and Parkinson disease.