BD not only increases IL-6 and myostatin (p < 0.05) serum levels but it also decreases LIF (p < 0.05), CX3CL1 (p < 0.01), FGF21 (p < 0.01), irisin (p < 0.01), BDNF (p < 0.01), FSTL-1 (p < 0.01), apelin (p < 0.01), and SPARC (p < 0.05) values. Here, FNDC5 is linked to Behcet disease.