There are two distinct inflammatory pathways in axSpA, the tumor necrosis factor (TNF)-α axis and the interleukin (IL)-23/IL-17A axis, which have major implications for specific pathogenic events (inflammation and ossification) occurring locally (axial as well as peripheral, comprising synovitis and enthesitis) and also systemically (ocular, intestinal, cutaneous, etc.). This evidence concerns the gene TNF and synovitis.