When subgroups with AP were compared in terms of serum TNF-α, which is an important indicator of tissue destruction and inflammation, there was no difference between AS-PAI 1 and AS-PAI 2 subgroups (p > 0.05), while TNF-α levels of the AS-PAI 3 subgroup were higher than the others (p < 0.05) (Fig. 2A). This evidence concerns the gene TNF and alkaline phosphatase measurement.