Of these, 22 are novel with respect to bipolar disorder, while serum or plasma concentrations of AM [32], CCL3 [33–35], CCL4 [33, 36], CCL20 [37], CCL25 [38, 39], CHI3L1 [40, 41], GDF-15 [39], IL-10 [39], MMP-7 [37], and TNF-R1 [39] have previously been reported to be higher in patients with bipolar disorder than controls. Here, GDF15 is linked to bipolar disorder.