HLA-DRB1 and multiple sclerosis: Specifically, the TF with the highest weight in the TF-expression model (β = 0.23 in muscle and β = 0.18 in blood) is CIITA, where variability in the CIITA gene has been reported to interact with specific mutations of HLA-DRB1 to increase the risk for multiple sclerosis [62,63] and type 1 diabetes [64,65].