Stromal cell-derived factor 1 (CXCL12) was confirmed to be positively correlated with α-syn in post-mortem brains tissues of PD patients and increased in the blood of PD patients [27]; moreover, in the same study, α-syn increased the production of CXCL12 in microglia [48]. The gene discussed is CXCL12; the disease is Parkinson disease.