Whereas, the results of our study are partly consistent with previous reports on a group of patients with ankylosing spondylitis, in which effective therapy with TNFα inhibitors resulted in a decrease in kynurenine/tryptophan ratio, although the effect of treatment on other metabolites appeared to be limited (Eryavuz Onmaz et al. 2021) or even serotonin levels decreased during biological treatment (Klavdianou et al. 2016). The gene discussed is TNF; the disease is ankylosing spondylitis.