In the multivariable linear regression analysis, which included age [β (95% CI) = 0.0060 (− 0.004, 0.016), p = 0.23] and smoking status [β (95% CI) =  − 0.306 (− 0.731, 0.119), p = 0.16] as covariables, VD deficiency was also found to be associated with increased systemic CCL20 levels in patients with ulcerative colitis [β (95% CI) = 0.294 (0.037, 0.550), p = 0.025; Table 3]. The gene discussed is CCL20; the disease is ulcerative colitis.