However, this does not necessarily imply a lack of contribution from immune-related pathways in PD, as several DEGs related to immune processes (CD40LG, CXCR3, LAG3, IFIH1, HLA-B, HLA-DRA, SPATA2L, TNFAIP1), including those involved in antigen presentation and T cell and B cell immune functions, were downregulated in PD. Here, HLA-DRA is linked to Parkinson disease.