KEGG pathway analysis showed that piRNA-generating genes played important roles in 26 pathways, including vitamin B6 metabolism, protein processing in the endoplasmic reticulum, Parkinson’s disease, glyoxylate and dicarboxylate metabolism, carbon metabolism, thyroid hormone signaling pathway, PI3K-Akt signaling pathway, focal adhesion, ECM–receptor interaction and hematopoietic cells (Supplementary Table 4). This evidence concerns the gene TG and Parkinson disease.