The BD group displayed significantly increased levels of FGF15 in serum (Figure 4C) and brain (110.91 ± 15.69 pg/g vs. 78.21 ± 4.58 pg/g, P = 0.007, Figure 5B), which could bind to the coreceptor Klotho in the hypothalamus. This evidence concerns the gene KL and Behcet disease.