In PD-WT, IL-4 is found to be enhanced as an upstream regulator, and YWHAB, CDC42, TBK1, CDC5L, LRRK2, NFKB1, and ITPR2 are upregulated with increasing HPgV titer, whereas in PD-LRRK2, IL-4 signaling and these genes are downregulated. Here, IL4 is linked to Parkinson disease.