However, they also showed significant elevated levels of oligomeric α-synuclein (7.03 pg/ng vs. 0.92 pg/ng), and the ratio of total and oligomeric α-synuclein (0.79 vs. 0.10) in saliva of PD patients compared to unaffected controls, confirming other observations [34,39]. This evidence concerns the gene SNCA and Parkinson disease.