This approach identified a distinct transcriptomic signature in monocytes from early PD patients, with differentially expressed genes such as HLA-DQB1 (MHCII system), MYD88 (associated to TLR2&4), REL (member of the NFκB transcription factors) and TNF [156], thus confirming the early relevance of the immune system in PD. This evidence concerns the gene HLA-DQB1 and Parkinson disease.