Results showed that for discriminating IBD from IBS, BAFF ≥227.3 pg/ml yield 84% sensitivity, 100% specificity, 100% positive predictive value (PPV) and 64% negative predictive value (NPV) while calprotectin ≥50 μg/g yield 76% sensitivity, 93% specificity, 97% PPV and 53% NPV. This evidence concerns the gene TNFSF13B and inflammatory bowel disease.