Overall, the most common systemic cytokines associated with mTBI include IL-6 [17,18,19,20,21,22,23], TNF-α [20,23,24,25], IL-10 [20,26], IL-1β [19,20], Interleukin-8 (IL-8) [20,25], Interferon Gamma (IFN-γ) [20,25], Interleukin-1RA (IL-1RA) [17,21], Interleukin-4 (IL-4) [20], and C–C motif chemokine ligand 2 (CCL2) [19,27]. This evidence concerns the gene IL4 and concussion.