Polymorphisms in the human leukocyte antigen, HLA-DRA, HLA-DRB1 (rs660895) and HLA-DRB, IL-6 rs1800795, TNF-α rs1799964, PON1 rs854560, CYP2D6 rs3892097, BST1 rs11931532, and CCDC62 rs12817488 are also involved in PD [21-25]. Here, HLA-DRB1 is linked to Parkinson disease.