LRRK2 and Parkinson disease: We also identified six biochemical pathways to be significantly perturbed in LRRK2 PD CSF as compared with LRRK2 controls (p < 0.05; q < 0.1; Supplementary Table S2) and these include: spermidine and spermine biosynthesis, fatty acid metabolism, mitochondrial beta oxidation of long chain fatty acids (LCFAs), methionine metabolism, bile-acid metabolism, methionine metabolism, and beta oxidation of short chain fatty acids (SCFAs).