Intriguingly, genetic background might also be relevant, since Vilas et al. [117] described that, in the subgroup of patients with a mutation in the leucine rich repeat kinase 2 (LRRK2) gene, CSF t-Tau levels were higher in PIGD-PD than TD-PD, whereas no differences were detected when all patients (with or without LRRK2 mutation) were analyzed together. This evidence concerns the gene LRRK2 and Parkinson disease.