ABCG2 and Parkinson disease: We found that the KEGG pathways were mainly amino acid metabolism (arginine biosynthesis, arginine and proline metabolism, phenylalanine metabolism, alanine, aspartate and glutamate metabolism), carbohydrate metabolism (glyoxylate and dicarboxylate metabolism, TCA cycle), lipid metabolism (glycerophospholipid metabolism), membrane transport (ABC transporters), neurodegenerative disease (pathways of neurodegeneration-multiple diseases, Parkinson disease) and nucleotide metabolism (purine metabolism).