We observed a negative correlation of serum irisin levels with visual analogue scale (VAS) patient, VAS physician and Bath Ankylosing Spondylitis Metrology Index (BASMI) (r=-0.12, p=0.003; r=-0.19, p<0.001; r=-0.13, p=0.002; respectively). This evidence concerns the gene FNDC5 and spondylitis.